Dr. Troxell is a Pathologist with special interest in breast pathology, renal pathology (including medical kidney disease, kidney transplant and kidney tumors), and genitourinary pathology. She has been practicing pathology for over 10 years.

Clinical Focus

  • Breast Pathology
  • Renal Pathology
  • Genitourinary Pathology
  • Transplant Pathology
  • Anatomic and Clinical Pathology

Academic Appointments

  • Professor - University Medical Line, Pathology

Administrative Appointments

  • Co-Director, Stanford Immunodiagnosis Laboratory (2018 - Present)
  • Director, Surgical Pathology Fellowship (2016 - Present)
  • Co-Director, Post-Sophomore Fellowship (2016 - Present)

Boards, Advisory Committees, Professional Organizations

  • Board of Directors, International Society for Immunohistochemistry and Molecular Morphology (2019 - Present)
  • Editorial Board, Modern Pathology (2023 - Present)

Professional Education

  • MD/PhD, Stanford University (2000)
  • Residency, Stanford University, Anatomic Pathology
  • Fellowships, Stanford University, Surgical Pathology, Renal & IPOX
  • Board Certification, American Board of Pathology, Anatomic Pathology (2004)

Current Research and Scholarly Interests

Breast pathology, renal pathology, transplant pathology, immunohistochemistry

All Publications

  • Antibrush Border Antibody Disease: A Case Series KIDNEY MEDICINE Pengshung, M., Charu, V., Troxell, M. L., Akilesh, S., Smith, K. D., Jefferson, J. 2024; 6 (7)
  • Infection-Related Glomerulonephritis with Cutaneous Vasculitis. Clinical journal of the American Society of Nephrology : CJASN Gedallovich, J., Mohty, R. M., Kasimova, K., Lu, Z., Charu, V., Higgins Jp, J. P., Kambham, N., Kung, V. L., Troxell, M. L. 2024

    View details for DOI 10.2215/CJN.0000000000000503

    View details for PubMedID 38922691

  • Characteristics and Outcomes of NELL1 Membranous Nephropathy in Lipoic Acid Users and Nonusers. Kidney international reports Avasare, R. S., Clark, S., Spain, R. I., Wusirika, R., Rope, R., Gurley, S., Stanaway, M., Sekulic, M., Santoriello, D., Bomback, A. S., Canetta, P., Iyer, S. J., Kung, V., Charu, V., Troxell, M. L., Kudose, S., Andeen, N. K. 2024; 9 (5): 1379-1386


    Neural epidermal growth factor like 1 membranous nephropathy (NELL1 MN) is associated with various secondary etiologies. However, previous studies on the frequency of these associations and their impact on outcomes are limited. We report a large multiinstitutional series of patients with NELL1 MN with a focus on secondary associations, pathology findings, and their impact on outcome.We retrospectively reviewed clinicopathologic features of NELL1 MN from 3 institutions and analyzed clinical and histologic associations with outcome.Of 70 patients, 53% were male with a median age of 66 years; median proteinuria was 5.9 g/d. NELL1 MN was associated with lipoic acid (36%), heavy nonsteroidal antiinflammatory drug (NSAID) use (27%), autoimmune disease (23%), malignancy (10% recent, 23% any), mercury exposure (1%), and 11% had no known secondary association. At median follow-up of 11 months, 72% achieved complete or partial remission. Remission rate was 91% in patients with lipoic acid-associated NELL1 MN and ≥6 months of follow-up. On multivariable analyses, patients with primary NELL1 MN (adjusted odds ratio [OR]: 19.7, P = 0.01) and increasing degree of tubular atrophy and interstitial fibrosis (IFTA) (adjusted OR 1.1, P = 0.01) were less likely to achieve any remission, whereas complete remission (CR) was associated with lipoic acid use (adjusted OR: 10.9, P = 0.04, 95% confidence interval [CI]: 1.2-100) and lesser degrees of IFTA (adjusted OR: 0.79, P = 0.16, 95% CI: 0.66-0.96).Our findings strengthen the association between lipoic acid and NELL1 MN. Furthermore, our findings suggest that discontinuation of lipoic acid without immunosuppression should be considered as the first-line treatment.

    View details for DOI 10.1016/j.ekir.2024.02.1401

    View details for PubMedID 38707817

    View details for PubMedCentralID PMC11068956

  • The Histopathologic Features of Early COVID Pneumonia in a Pediatric Patient: New Insight into the Role of Macrophages INTERNATIONAL JOURNAL OF SURGICAL PATHOLOGY Bulterys, P. L., Xu, G., Pinsky, B. A., Troxell, M. L., Menke, J. R., Berry, G. J., Fernandez-Pol, S., Hazard, F. K. 2024
  • Principles of Analytic Validation of Immunohistochemical Assays: Guideline Update. Archives of pathology & laboratory medicine Goldsmith, J. D., Troxell, M. L., Roy-Chowdhuri, S., Colasacco, C. F., Edgerton, M. E., Fitzgibbons, P. L., Fulton, R., Haas, T., Kandalaft, P. L., Kalicanin, T., Lacchetti, C., Loykasek, P., Thomas, N. E., Swanson, P. E., Bellizzi, A. M. 2024


    CONTEXT.: In 2014, the College of American Pathologists developed an evidence-based guideline to address analytic validation of immunohistochemical assays. Fourteen recommendations were offered. Per the National Academy of Medicine standards for developing trustworthy guidelines, guidelines should be updated when new evidence suggests modifications.OBJECTIVE.: To assess evidence published since the release of the original guideline and develop updated evidence-based recommendations.DESIGN.: The College of American Pathologists convened an expert panel to perform a systematic review of the literature and update the original guideline recommendations using the Grading of Recommendations Assessment, Development and Evaluation approach.RESULTS.: Two strong recommendations, 1 conditional recommendation, and 12 good practice statements are offered in this updated guideline. They address analytic validation or verification of predictive and nonpredictive assays, and recommended revalidation procedures following changes in assay conditions.CONCLUSIONS.: While many of the original guideline statements remain similar, new recommendations address analytic validation of assays with distinct scoring systems, such as programmed death receptor-1 and analytic verification of US Food and Drug Administration approved/cleared assays; more specific guidance is offered for validating immunohistochemistry performed on cytology specimens.

    View details for DOI 10.5858/arpa.2023-0483-CP

    View details for PubMedID 38391878

  • AA amyloidosis With Ig-Dominant Staining and Diagnostically Unusual Features. Kidney international reports Andeen, N. K., DiFranza, L., Kung, V. L., Henriksen, K., Gupta, R., Dinesh, K., Akilesh, S., Kudose, S., Smith, K. D., Troxell, M. L. 2024; 9 (1): 162-170


    Although serum amyloid A (AA) amyloid may occasionally show nonspecific staining by immunofluorescence (IF), the correct diagnosis can usually be determined by integrating pathologic features and clinical scenario, and using AA amyloid immunohistochemistry (IHC) and/or mass spectrometry. A recent mass spectrometry-based study described false-positive Ig IF staining in a subset of AA amyloid cases.We sought to delineate clinicopathologic features of AA amyloid with Ig-dominant staining by using a retrospective review.AA amyloid with Ig-dominant staining was identified in 10 patients from 5 institutions, representing 1.2% to 4% of AA amyloid kidney biopsies. Evidence of a monoclonal protein was documented in 0% to 2.7% of patients with AA amyloid screened for inclusion, but 30% of those with Ig-dominant staining. The patient population had equal sex distribution and presented at median age of 68.5 years with nephrotic proteinuria and kidney impairment. Etiologies of AA amyloid included injection drug use (30%), autoimmune disease (20%), and chronic infection (10%); 40% had no identified clinical association. On biopsy, heavy chain (co)dominant staining by IF (in 80%), discordant distribution in Ig staining (in 20%), tubulointerstitial nephritis (in 30%), and/or crescents (in 10%) were present. Two of 3 patients with paraproteinemia had concordant heavy and/or light chain dominant staining within the AA amyloid. Two cases were initially misdiagnosed as Ig-associated amyloidosis.We describe the morphologic spectrum of AA amyloidosis with Ig-dominant staining which may have clinical, laboratory, and pathologic overlap with amyloid light chain (AL), amyloid heavy chain, and heavy and light chain (AHL) amyloidosis.

    View details for DOI 10.1016/j.ekir.2023.10.005

    View details for PubMedID 38312779

    View details for PubMedCentralID PMC10831352

  • Non-full house membranous lupus nephritis represents a clinically distinct subset. Kidney360 Ye, J., Croom, N., Troxell, M. L., Kambham, N., Zuckerman, J. E., Andeen, N., Dall'Era, M., Hsu, R., Walavalkar, V., Laszik, Z. G., Urisman, A. 2023


    Renal involvement in systemic lupus erythematosus (SLE) is a key predictor of morbidity and mortality. Immunofluorescence (IF) staining of glomeruli is typically positive for IgG, IgA, IgM, C3, and C1q - the "full house" (FH) pattern. However, a subset of patients with membranous lupus nephritis (MLN) have a "non-full house" (NFH) IF pattern more typical of idiopathic membranous nephropathy (IMN).From a multi-institutional cohort of 113 MLN cases, we identified 29 NFH MLN biopsies. NFH MLN was defined by IF criteria: ≥1+ glomerular capillary loop IgG staining; and <1+ IgA, IgM, and C1q. FH MLN was defined as ≥1+ staining for all five antibodies. "Intermediate" (Int) cases did not meet criteria for FH or NFH. We compared the pathological and clinical characteristics and outcomes among patients with FH, NFH, and Int IF patterns on kidney biopsy.NFH MLN represents a subset of MLN biopsies (13.4%). Compared to FH MLN patients, NFH MLN patients were older at SLE diagnosis (29 vs. 22.5 years), had a longer time to initial kidney biopsy (8 vs. 3.16 years), and had fewer SLE manifestations (2.5 vs. 3.36 involved systems). NFH MLN biopsies showed lower C3 IF intensity (1.16+ vs. 2.38+). Int biopsies had findings intermediate between those of NFH and FH groups.NFH IF pattern defines a small subset of MLN biopsies and appears to be associated with milder clinical manifestations and slower disease progression. Less robust C3 deposition in NFH MLN may suggest a pathophysiology distinct from that of FH MLN.

    View details for DOI 10.34067/KID.0000000000000161

    View details for PubMedID 37257088

  • Thrombotic Microangiopathic Changes in Kidney Biopsies of Childhood-Onset Systemic Lupus Erythematous Patients with and Without Severe Hematologic Disturbances Tsin, C., Troxell, M., Charu, V., Lu, R., Hsu, J. WILEY. 2023: 27-28
  • Comprehensive Immunohistochemical Analysis of Metaplastic Breast Carcinoma Subtypes Krings, G., Bean, G., Schwartz, C., Shamir, E., Gao, G., Troxell, M., Chen, Y. ELSEVIER SCIENCE INC. 2023: S159-S160
  • Genetic and Immunohistochemical Characterization of Mammary Hidradenoma and Comparison to Mucoepidermoid Carcinoma Black, M., Najjar, S., Wang, A., Troxell, M., Vohra, P., Gasper, C., Krings, G., Chen, Y., Bean, G. ELSEVIER SCIENCE INC. 2023: S103-S104
  • Digital Image Analysis and Quantitative Bead Standards in Root Cause Analysis of Immunohistochemical Staining Variability: A Real-world Example. Applied immunohistochemistry & molecular morphology : AIMM Rojansky, R., Sompuram, S. R., Gomulia, E., Natkunam, Y., Troxell, M. L., Fernandez-Pol, S. 2022


    Assessment of automated immunohistochemical staining platform performance is largely limited to the visual evaluation of individual slides by trained personnel. Quantitative assessment of stain intensity is not typically performed. Here we describe our experience with 2 quantitative strategies that were instrumental in root cause investigations performed to identify the sources of suboptimal staining quality (decreased stain intensity and increased variability). In addition, these tools were utilized as adjuncts in validation of a new immunohistochemical staining instrument. The novel methods utilized in the investigation include quantitative assessment of whole slide images (WSI) and commercially available quantitative calibrators. Over the course of ~13 months, these methods helped to identify and verify correction of 2 sources of suboptimal staining. One root cause of suboptimal staining was insufficient/variable power delivery from our building's electrical circuit. This led us to use uninterruptible power managers for all automated immunostainer instruments, which restored expected stain intensity and consistency. Later, we encountered one instrument that, despite passing all vendor quality control checks and not showing error alerts was suspected of yielding suboptimal stain quality. WSI analysis and quantitative calibrators provided a clear evidence that proved critical in confirming the pathologists' visual impressions. This led to the replacement of the instrument, which was then validated using a combination of standard validation metrics supplemented by WSI analysis and quantitative calibrators. These root cause analyses document 2 variables that are critical in producing optimal immunohistochemical stain results and also provide real-world examples of how the application of quantitative tools to measure automated immunohistochemical stain output can provide a greater objectivity when assessing immunohistochemical stain quality.

    View details for DOI 10.1097/PAI.0000000000001045

    View details for PubMedID 35876743

  • Clinicopathologic features of non-lupus membranous nephropathy in a pediatric population. Pediatric nephrology (Berlin, Germany) Miller, P., Lei, L., Charu, V., Higgins, J., Troxell, M., Kambham, N. 2022


    BACKGROUND: Membranous nephropathy is an uncommon cause of nephrotic syndrome in pediatrics.METHODS: We reviewed our kidney biopsy records for patients ≤ 20 years of age with membranous nephropathy without evidence of systemic lupus erythematosus within 6 months of biopsy (January 1995-September 2020). Staining for PLA2R, NELL1, THSD7A, SEMA3B, EXT2 (3 biopsies), and IgG-subclass were performed.RESULTS: Sixteen children (≤ 12 years) and 25 adolescents (13-20 years) were identified. Four children and 15 adolescents showed autoantigen positivity: PLA2R+/SEMA3B- (13), SEMA3B+/PLA2R+ (2), SEMA3B+/PLA2R- (1), NELL1 (1),EXT2+ (2), and THSD7A (0). Co-morbidities associated with PLA2R positivity included IPEX syndrome, active hepatitis B, Von Hippel Lindau syndrome, solitary kidney, type 1 diabetes, hyperuricemia, pregnancy (1), obesity (3), type II diabetes, H. pylori, viral prodrome, and nephrolithiasis. The SEMA3B+/PLA2R- adolescent was pregnant, the NELL1+ adolescent was obese, and the two EXT2+ adolescents eventually met the clinical criteria for lupus (4, 9 years post-biopsy). Co-morbidities among the remaining 24 patients included remote hepatitis B (2), Down's syndrome, lysinuric protein intolerance, recurrent UTIs, hypothyroidism, pregnancy (3), and obesity (2). Follow-up data was available for 12 children and 16 adolescents. Of the 12 children, 6 achieved complete remission, 4 achieved partial remission, and 2 had no response to treatment (1 transplant). Of the 16 adolescents, 4 achieved complete remission, 4 achieved partial remission, and 8 had no response to treatment (3 transplants). A child with "full-house" immunofluorescence staining achieved spontaneous disease remission.CONCLUSION: Our non-lupus membranous nephropathy cohort represents one of the largest pediatric studies to date. A higher resolution version of the Graphical abstract is available as Supplementary information.

    View details for DOI 10.1007/s00467-022-05503-7

    View details for PubMedID 35333973

  • A Diverse Spectrum of Immune Complex-and Complement-Mediated Kidney Diseases Is Associated With Mantle Cell Lymphoma. Kidney international reports Andeen, N. K., Abdulameer, S., Charu, V., Zuckerman, J. E., Troxell, M., Kambham, N., Alpers, C. E., Najafian, B., Nicosia, R. F., Smith, K. D., Kung, V. L., Avasare, R. S., Vallurupalli, A., Jefferson, J. A., Hecox, D., Swetnam, L., Yamashita, M., Lin, M., Bissonnette, M. L., Akilesh, S., Hou, J. 2022; 7 (3): 568-579


    Introduction: There are limited reports on kidney biopsy findings in patients with mantle cell lymphoma (MCL).Methods: We initiated a multi-institutional, retrospective review of kidney biopsy findings in patients with active and treated MCL.Results: A total of 30 patients with MCL and kidney biopsies were identified, with a median age of 67 (range 48-87) years, 73% of whom were men. A total of 20 patients had active MCL at the time of biopsy, of whom 14 (70%) presented with acute kidney injury (AKI), proteinuria and/or hematuria, and biopsy findings potentially attributable to lymphoma. Of the 14, 11 had immune complex (IC) or complement-mediated (C3) disease including proliferative glomerulonephritis (GN) with monotypic Ig deposits (PGNMID [2]), C3GN, (2), secondary membranous nephropathy (MN [3]), tubular basement membrane (TBM) deposits (2), and modest lupus-like GN (2). Lymphomatous infiltration was present in 8 of the 20 patients, 5 with coincident IC or C3 lesions. A total of 6 patients with available follow-up were treated for MCL, all with clinical remission of GN (2 PGNMID, 2 C3GN, and 2 MN).Conclusion: MCL is associated with diverse monoclonal and polyclonal glomerular and extra-glomerular IC and C3 disease. For patients with active MCL and kidney dysfunction requiring biopsy, 70% had findings due or potentially due to lymphoma, including 55% with IC or C3 disease and 40% had lymphomatous kidney infiltration. IC and C3GN in the setting of active MCL was responsive to lymphoma-directed therapy.

    View details for DOI 10.1016/j.ekir.2021.12.020

    View details for PubMedID 35257069

  • Neoadjuvant Therapy in Breast Cancer: Histologic Changes and Clinical Implications. Surgical pathology clinics Troxell, M. L., Gupta, T. 2022; 15 (1): 57-75


    Cytotoxic or endocrine therapy before surgery (neoadjuvant) for breast cancer has become standard of care, affording the opportunity to assess and quantify response in the subsequent resection specimen. Correlation with radiology, cassette mapping, and histologic review with a semi-quantitative reporting system such as residual cancer burden (RCB) provides important prognostic data that may guide further therapy. The tumor bed should be identified histologically, often as a collagenized zone devoid of normal breast epithelium, with increased vasculature. Identification of residual treated carcinoma may require careful high power examination, as residual tumor cells may be small and dyscohesive; features are widely variable and include hyperchromatic small, large, or multiple nuclei with clear, foamy, or eosinophilic cytoplasm. Calculation of RCB requires residual carcinoma span in 2 dimensions, estimated carcinoma cellularity (% area), number of involved lymph nodes, and span of largest nodal carcinoma. These RCB parameters may differ from AJCC staging measurements, which depend on only contiguous carcinoma in breast and lymph nodes.

    View details for DOI 10.1016/j.path.2021.11.004

    View details for PubMedID 35236634

  • Pathology findings in pediatric patients with COVID-19 and kidney dysfunction. Pediatric nephrology (Berlin, Germany) Nomura, E., Finn, L. S., Bauer, A., Rozansky, D., Iragorri, S., Jenkins, R., Al-Uzri, A., Richardson, K., Wright, M., Kung, V. L., Troxell, M. L., Andeen, N. K. 2022


    BACKGROUND: Acute kidney injury (AKI) is seen in one-fifth of pediatric patients with COVID-19 requiring hospital admission, and is associated with increased morbidity, mortality, and residual kidney impairment. The majority of kidney pathology data in patients with COVID-19 is derived from adult case series and there is an overall lack of histologic data for most pediatric patients with COVID-19.METHODS: We assembled a multi-institutional cohort of five unvaccinated pediatric patients with COVID-19 and associated kidney dysfunction with available histology.RESULTS: Three complex patients with current or prior SARS-CoV-2 infection had multifactorial thrombotic microangiopathy with clinical features of hemolytic uremic syndrome (in two) or disseminated intravascular coagulation (in one); one died and another developed chronic kidney disease stage 5. Two with recently preceding SARS-CoV-2 infection presented with nephrotic syndrome; one had IgA vasculitis and one had minimal change disease. Within a short follow-up time, none has returned to baseline kidney function.CONCLUSION: Although uncommon, COVID-19-associated kidney injury can have significant morbidity in the unvaccinated pediatric and adolescent population. A higher resolution version of the Graphical abstract is available as Supplementary information.

    View details for DOI 10.1007/s00467-022-05457-w

    View details for PubMedID 35166918

  • Immune imprinting, breadth of variant recognition, and germinal center response in human SARS-CoV-2 infection and vaccination. Cell Röltgen, K., Nielsen, S. C., Silva, O., Younes, S. F., Zaslavsky, M., Costales, C., Yang, F., Wirz, O. F., Solis, D., Hoh, R. A., Wang, A., Arunachalam, P. S., Colburg, D., Zhao, S., Haraguchi, E., Lee, A. S., Shah, M. M., Manohar, M., Chang, I., Gao, F., Mallajosyula, V., Li, C., Liu, J., Shoura, M. J., Sindher, S. B., Parsons, E., Dashdorj, N. J., Dashdorj, N. D., Monroe, R., Serrano, G. E., Beach, T. G., Chinthrajah, R. S., Charville, G. W., Wilbur, J. L., Wohlstadter, J. N., Davis, M. M., Pulendran, B., Troxell, M. L., Sigal, G. B., Natkunam, Y., Pinsky, B. A., Nadeau, K. C., Boyd, S. D. 2022


    During the SARS-CoV-2 pandemic, novel and traditional vaccine strategies have been deployed globally. We investigated whether antibodies stimulated by mRNA vaccination (BNT162b2), including third-dose boosting, differ from those generated by infection or adenoviral (ChAdOx1-S and Gam-COVID-Vac) or inactivated viral (BBIBP-CorV) vaccines. We analyzed human lymph nodes after infection or mRNA vaccination for correlates of serological differences. Antibody breadth against viral variants is lower after infection compared with all vaccines evaluated but improves over several months. Viral variant infection elicits variant-specific antibodies, but prior mRNA vaccination imprints serological responses toward Wuhan-Hu-1 rather than variant antigens. In contrast to disrupted germinal centers (GCs) in lymph nodes during infection, mRNA vaccination stimulates robust GCs containing vaccine mRNA and spike antigen up to 8 weeks postvaccination in some cases. SARS-CoV-2 antibody specificity, breadth, and maturation are affected by imprinting from exposure history and distinct histological and antigenic contexts in infection compared with vaccination.

    View details for DOI 10.1016/j.cell.2022.01.018

    View details for PubMedID 35148837

  • Nodular fasciitis of the breast: clinicopathologic and molecular characterization with identification of novel USP6 fusion partners. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Cloutier, J. M., Kunder, C. A., Charville, G. W., Hosfield, E. M., García, J. J., Brown, R. A., Troxell, M. L., Allison, K. H., Bean, G. R. 2021


    Nodular fasciitis is a benign, self-limited, pseudosarcomatous neoplasm that can mimic malignancy due to its rapid growth, cellularity, and mitotic activity. Involvement of the breast is rare and diagnosis on biopsy can be challenging. In this largest series to date, we examined the clinicopathologic and molecular characteristics of 12 cases of nodular fasciitis involving the breast/axilla. All patients were female, with a median age of 32 years (range 15-61). The lesions were 0.4 to 5.8 cm in size (median 0.8). All cases presented as palpable masses, and two patients had overlying skin retraction. Microscopically, lesions were relatively well-circumscribed nodular masses of bland myofibroblastic spindle cells within a variably myxoid stroma. Infiltrative growth into adipose tissue or breast epithelium was frequent. Mitotic figures were present in all cases, ranging from 1 to 12 per 10 high-power fields (median 3). Immunohistochemically, all cases expressed smooth muscle actin and were negative for pan-cytokeratin, p63, desmin, CD34, and nuclear beta-catenin. Targeted RNA sequencing performed on 11 cases identified USP6 gene fusions in eight; one additional case was positive by break-apart fluorescence in situ hybridization. The common MYH9-USP6 rearrangement was detected in four cases; another case had a rare alternative fusion with CTNNB1. Three cases harbored novel USP6 gene fusions involving NACA, SLFN11, or LDHA. All fusions juxtaposed the promoter region of the 5' partner gene with the full-length coding sequence of USP6. Outcome data were available for eight patients; none developed recurrence or metastasis. Five patients elected for observation without immediate excision, and self-resolution of the lesions was reported in three cases. Albeit uncommon, nodular fasciitis should be considered in the differential diagnosis of breast spindle cell lesions. A broad immunohistochemical panel to exclude histologic mimics, including metaplastic carcinoma, is important. Confirmatory detection of USP6 rearrangements can aid in classification, with potential therapeutic implications.

    View details for DOI 10.1038/s41379-021-00844-4

    View details for PubMedID 34099872

  • One Hundred Years of the Pathology Medical Student Fellowship. Archives of pathology & laboratory medicine Hammer, P., Ireland, K., Houghton, D. C., Jaggers, A., Coleman, A., Snir, O. L., Troxell, M. L., Andeen, N. K. 2021


    The Pathology Medical Student Fellowship (PSF) is a unique, year-long immersive educational experience. Review of institutional archives describes a medical student "Fellowship in Pathology" founded in 1919.To characterize the impacts of this 100-year-old program.We determined subsequent medical specialty of each PSF graduate in our department and surveyed those with available contact information.Of 145 pathology student fellows graduating between 1924 and 2020, a total of 50 (34.4%) matched into pathology; medical, surgical, and radiology subspecialties were also well-represented career choices. Between 2001 and 2020, of 36 students who matched into pathology from our institution, 19 (52.8%) had completed the fellowship. Survey respondents (n = 42) indicated that before the PSF, 11 of 42 students (26.2 %) were undecided in specialty, with only 6 (14.3%) identifying pathology as their primary field of interest. Of survey respondents who had completed training, 26 (61.9%) practice in academic settings. Nonpathology physicians reported frequent utilization of skills gained during the PSF year, with 5 of 23 (21.7%) responding "daily," and 9 (39.1%) responding "weekly." The most useful skills included knowledge of pathophysiology of disease and anatomy, improved communication with multidisciplinary teams, and/or interpretation of pathology results (each selected by 17 to 20 students, 73.9%-87.0%). Free-text responses on impacts of the PSF described enhanced knowledge of disease pathobiology and diagnostic complexity and increased confidence and autonomy.We describe the program structure, educational benefits, graduate specialty choices, and career impacts of 100 years of the PSF at our institution. Although undecided before pathology exposure, many PSF graduates subsequently enter pathology careers. Regardless of specialty choice, PSF graduates have a high rate of subsequently pursuing academic medical careers.

    View details for DOI 10.5858/arpa.2021-0220-OA

    View details for PubMedID 34784414

  • Histologic Case Definition of an Atypical Glomerular Immune-Complex Deposition Following Kidney Transplantation. Kidney international reports Chin, K., Charu, V., O'Shaughnessy, M. M., Troxell, M. L., Cheng, X. S. 2020; 5 (5): 632–42


    Introduction: Immune-complex deposition in the transplanted kidney can present as well-phenotyped recurrent or de novo glomerular disease. However, a subset, herein termed immune-complex glomerulopathy not otherwise specified (ICG-NOS), defies classification. We quantified, categorized, and characterized cases of transplant ICG-NOS occurring at a single US academic medical center.Methods: We retrospectively reviewed our single-institution pathology database (July 2007-July 2018) to identify and categorize all cases of immune-complex deposition in kidney allografts (based on immunofluorescence microscopy). We extracted clinicopathologic and outcome data for ICG-NOS (i.e., immune complex deposition not conforming to any well-characterized glomerular disease entity).Results: Of 104 patients with significant immune deposits, 28 (27%) were classified as ICG-NOS. We created 5 mutually exclusive ICG-NOS categories: Full-house, Quasi-full-house, IgA-rich, C1q-rich, and C1q-poor. Overall, 16 (57%) patients met criteria for definite or possible allograft rejection, including 9 (32%) with antibody-mediated rejection (ABMR), 3 (11%) suspicious for ABMR, 1 (4%) with T-cell-mediated rejection (TCMR), and 9 (32%) with borderline TCMR. After a median follow-up of 2.3 (range, 0.1-14.0) years after biopsy, 7 (25%) allografts had failed and an additional 8 (29%) had persistent renal dysfunction (hematuria, 14%; proteinuria, 21%; and estimated glomerular filtration rate<60 ml/min per 1.73 m2, 11%).Conclusion: In contrast to prior studies, our findings suggest that ICG-NOS is not necessarily a benign glomerular process and that there may be an association between ICG-NOS and alloimmunity. Our immunofluorescence-based classification provides a framework for future studies aiming to further elucidate ICG-NOS pathogenesis and prognosis.

    View details for DOI 10.1016/j.ekir.2020.01.022

    View details for PubMedID 32405585

  • Myelin bodies in LMX1B-associated nephropathy: potential for misdiagnosis. Pediatric nephrology (Berlin, Germany) Lei, L., Oh, G., Sutherland, S., Abra, G., Higgins, J., Sibley, R., Troxell, M., Kambham, N. 2020


    BACKGROUND: Myelin figures, or zebra bodies, seen on electron microscopy were historically considered pathognomonic of Fabry disease, a rare lysosomal storage disorder caused by alpha-galactosidase A deficiency and associated with X-linked recessive mode of inheritance. More recently, iatrogenic phospholipidosis has emerged as an important alternate cause of myelin figures in the kidney.METHODS: We report two families with autosomal dominant nephropathy presenting with proteinuria and microscopic hematuria, and the kidney biopsies were notable for the presence of myelin figures and zebra bodies.RESULTS: Laboratory and genetic work-up for Fabry disease was negative. Genetic testing in both families revealed the same heterozygous missense mutation in LMX1B (C.737G>A, p.Arg246Gln). LMX1B mutations are known to cause nail-patella syndrome, featuring dysplastic nails and patella with or without nephropathy, as well as isolated LMX1B-associated nephropathy in the absence of extrarenal manifestations.CONCLUSIONS: LMX1B mutation-associated nephropathy should be considered in hereditary cases of proteinuria and/or hematuria, even in the absence of unique glomerular basement membrane changes indicative of nail-patella syndrome. In addition, LMX1B mutation should be included in the differential diagnosis of myelin figures and zebra bodies on kidney biopsy, so as to avoid a misdiagnosis.

    View details for DOI 10.1007/s00467-020-04564-w

    View details for PubMedID 32356190

  • Primary mammary angiosarcomas harbor frequent mutations in KDR and PIK3CA and show evidence of distinct pathogenesis. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Beca, F., Krings, G., Chen, Y., Hosfield, E. M., Vohra, P., Sibley, R. K., Troxell, M. L., West, R. B., Allison, K. H., Bean, G. R. 2020


    Angiosarcoma (AS) is the most frequent primary sarcoma of the breast but nevertheless remains uncommon, accounting for <0.05% of breast malignancies. Secondary mammary AS arise following radiation therapy for breast cancer, in contrast to primary AS which occur sporadically. Essentially all show aggressive clinical behavior independent of histologic grade and most are treated by mastectomy. MYC amplification is frequently identified in radiation-induced AS but only rarely in primary mammary AS (PMAS). As a heterogeneous group, AS from various anatomic sites have been shown to harbor recurrent alterations in TP53, MAP kinase pathway genes, and genes involved in angiogenic signaling including KDR (VEGFR2) and PTPRB. In part due to its rarity, the pathogenesis of PMAS has not been fully characterized. In this study, we examined the clinical, pathologic, and genomic features of ten cases of PMAS, including one patient with bilateral disease. Recurrent genomic alterations were identified in KDR (70%), PIK3CA/PIK3R1 (70%), and PTPRB (30%), each at higher frequencies than reported in AS across all sites. Six tumors harbored a KDR p.T771R hotspot mutation, and all seven KDR-mutant cases showed evidence suggestive of biallelism (four with loss of heterozygosity and three with two aberrations). Of the seven tumors with PI3K alterations, six harbored pathogenic mutations other than in the canonical PIK3CA residues which aremost frequent in breast cancer. Three AS were hypermutated (≥10 mutations/megabase (Mb)); hypermutation was seen concurrent with KDR or PIK3CA mutations. The patient with bilateral disease demonstrated shared alterations, indicative of contralateral metastasis. No MYC or TP53 aberrations were detected in this series. Immunohistochemistry for VEGFR2 was unable to discriminate between KDR-mutant tumors and benign vascular lesions of the breast. These findings highlight the underrecognized frequency of KDR and PIK3CA mutation in PMAS, and a significant subset with hypermutation, suggesting a pathogenesis distinct from other AS.

    View details for DOI 10.1038/s41379-020-0511-6

    View details for PubMedID 32123305

  • Progression of Proliferative Glomerulonephritis with Monoclonal IgG Deposits in Pediatric Patients Miller, P., Xiao, A., Kung, V., Sibley, R., Higgins, J., Kambham, N., Charu, V., Lenihan, C., Talley, E., Walavalkar, V., Laszik, G., Arora, N., Nast, C., Troxell, M. NATURE PUBLISHING GROUP. 2020: 1589–90
  • Optimization and Cost Savings with Reduction of Negative Immunohistochemical Reagent Controls Scapa, J., Troxell, M., Fernandez-Pol, S., Natkunam, Y. NATURE PUBLISHING GROUP. 2020: 1899
  • Molecular Characterization of Metanephric Adenomas Beyond BRAF: Genetic Evidence for Potential Malignant Evolution. Histopathology Chan, E., Stohr, B. A., Croom, N. A., Cho, S., Garg, K., Troxell, M. L., Higgins, J. P., Bean, G. R. 2020


    AIMS: Metanephric adenomas (MA) are conventionally regarded as rare renal tumors with indolent behavior; limited case reports describe MA with aggressive features. Conventional MA harbor hotspot BRAF V600E mutations. A BRAF V600E senescence pathway, mediated by CDKN2A/p16, has been proposed to confer MA benignity. Aside from BRAF, the molecular landscape in both conventional MA and those with aggressive features has not been fully characterized. In this study we molecularly profiled a series of MA to investigate the correlation between genomic findings and clinical outcome.METHODS AND RESULTS: We retrospectively examined the histomorphology and patient outcomes of 11 conventional MA and one MA with aggressive features. Each was subjected to capture-based next-generation DNA sequencing of 479 cancer-related genes and immunohistochemical profiling. All tumors were positive for WT1 immunostaining and BRAF V600E mutation. One conventional MA contained an additional somatic BRCA2 pathogenic mutation. The MA with aggressive features showed a biphasic appearance: one component was epithelial with areas morphologically consistent with conventional MA; the second component was sarcomatous with areas of solid and angiosarcomatous growth. Differential profiling of the two populations revealed identical BRAF, EIF1AX, and TERT promoter hotspot mutations in the epithelial and sarcomatous components. Deep deletion of CDKN2A and MYC amplification were identified only in the sarcomatous component.CONCLUSIONS: While the vast majority of MA show indolent behavior, rare pathogenic alterations can occur in conventional MA in addition to BRAF. Molecular profiling of a case with aggressive clinical and pathologic features shows genetic evidence for malignant evolution in MA.

    View details for DOI 10.1111/his.14094

    View details for PubMedID 32064677

  • HER2 Dual In Situ Hybridization: Correlations and Cautions. Archives of pathology & laboratory medicine Troxell, M. n., Sibley, R. K., West, R. B., Bean, G. R., Allison, K. H. 2020


    Accurate HER2 testing in breast cancer is crucial for appropriate precision therapy. HER2 testing is most commonly accomplished by a combination of immunohistochemistry and in situ hybridization techniques, as gene amplification is closely tied to protein overexpression. During the last 5+ years, brightfield dual in situ hybridization (DISH) has replaced fluorescence methods (fluorescence in situ hybridization [FISH]) in some laboratories.To analyze routine HER2 DISH performance in the field.We reviewed our experience with HER2 DISH performed at outside laboratories and referred for patient care.Of 273 identified retrospective DISH results, 55 had repeated FISH testing at our institution; 7 (13%) were discordant. Additional cases had technical flaws hampering appropriate scoring. In 23 cases (42%), HER2 DISH was performed without immunohistochemistry. Slide review of a prospective cohort of 42 consecutive DISH cases revealed 14 (33%) with technical or interpretative limitations potentially jeopardizing results. Commonly identified problems include lack of or weak signals in most tumor cells, and silver precipitate or red signals outside of nuclei, resulting in false-negative or false-positive interpretations, respectively. Further, 44% (24 of 55) of DISH reports lacked complete data, specifically average HER2 signals/cell.While HER2 DISH can be an efficient and effective alternative to FISH, we illustrate pitfalls and reinforce that careful attention to slide quality and technical parameters are critically important. HER2 DISH cotesting with immunohistochemistry could help minimize false-negative or false-positive HER2 results.

    View details for DOI 10.5858/arpa.2019-0510-OA

    View details for PubMedID 32101450

  • A co-formulation of supramolecularly stabilized insulin and pramlintide enhances mealtime glucagon suppression in diabetic pigs. Nature biomedical engineering Maikawa, C. L., Smith, A. A., Zou, L. n., Roth, G. A., Gale, E. C., Stapleton, L. M., Baker, S. W., Mann, J. L., Yu, A. C., Correa, S. n., Grosskopf, A. K., Liong, C. S., Meis, C. M., Chan, D. n., Troxell, M. n., Maahs, D. M., Buckingham, B. A., Webber, M. J., Appel, E. A. 2020


    Treatment of patients with diabetes with insulin and pramlintide (an amylin analogue) is more effective than treatment with insulin only. However, because mixtures of insulin and pramlintide are unstable and have to be injected separately, amylin analogues are only used by 1.5% of people with diabetes needing rapid-acting insulin. Here, we show that the supramolecular modification of insulin and pramlintide with cucurbit[7]uril-conjugated polyethylene glycol improves the pharmacokinetics of the dual-hormone therapy and enhances postprandial glucagon suppression in diabetic pigs. The co-formulation is stable for over 100 h at 37 °C under continuous agitation, whereas commercial formulations of insulin analogues aggregate after 10 h under similar conditions. In diabetic rats, the administration of the stabilized co-formulation increased the area-of-overlap ratio of the pharmacokinetic curves of pramlintide and insulin from 0.4 ± 0.2 to 0.7 ± 0.1 (mean ± s.d.) for the separate administration of the hormones. The co-administration of supramolecularly stabilized insulin and pramlintide better mimics the endogenous kinetics of co-secreted insulin and amylin, and holds promise as a dual-hormone replacement therapy.

    View details for DOI 10.1038/s41551-020-0555-4

    View details for PubMedID 32393892

  • Membranous nephropathy in patients with HIV: a report of 11 cases. BMC nephrology Charu, V. n., Andeen, N. n., Walavalkar, V. n., Lapasia, J. n., Kim, J. Y., Lin, A. n., Sibley, R. n., Higgins, J. n., Troxell, M. n., Kambham, N. n. 2020; 21 (1): 401


    Membranous nephropathy (MN) has been recognized to occur in patients with human immunodeficiency virus (HIV) infection since the beginning of the HIV epidemic. The prevalence of phospholipase A2 receptor (PLA2R)-associated MN in this group has not been well studied.We conducted a retrospective review of electronic pathology databases at three institutions to identify patients with MN and known HIV at the time of renal biopsy. Patients with comorbidities and coinfections known to be independently associated with MN were excluded.We identified 11 HIV-positive patients with biopsy-confirmed MN meeting inclusion and exclusion criteria. Patient ages ranged from 39 to 66 years old, and 10 of 11 patients (91%) were male. The majority of patients presented with nephrotic-range proteinuria, were on anti-retroviral therapy at the time of biopsy and had low or undetectable HIV viral loads. Biopsies from 5 of 10 (50%) patients demonstrated capillary wall staining for PLA2R. Measurement of serum anti-PLA2R antibodies was performed in three patients, one of whom had positive anti-PLA2R antibody titers. Follow-up data was available on 10 of 11 patients (median length of follow-up: 44 months; range: 4-145 months). All patients were maintained on anti-retroviral therapy (ARV) and 5 patients (52%) received concomitant immunosuppressive regimens. Three patients developed end-stage renal disease (ESRD) during the follow-up period.MN in the setting of HIV is often identified in the setting of an undetectable viral loads, and similar to other chronic viral infection-associated MNs, ~ 50% of cases demonstrate tissue reactivity with PLA2R antigen, which may be seen without corresponding anti-PLA2R serum antibodies.

    View details for DOI 10.1186/s12882-020-02042-x

    View details for PubMedID 32948130

  • Progression of proliferative glomerulonephritis with monoclonal IgG deposits in pediatric patients. Pediatric nephrology (Berlin, Germany) Miller, P. n., Xiao, A. Y., Kung, V. L., Sibley, R. K., Higgins, J. P., Kambham, N. n., Charu, V. n., Lenihan, C. n., Uber, A. M., Talley, E. M., Arora, N. n., Walavalkar, V. n., Laszik, Z. G., Nast, C. C., Troxell, M. L. 2020


    Proliferative glomerulonephritis with monoclonal IgG deposits (PGNMID) is a glomerular disease defined by non-organized glomerular deposits of heavy and light chain-restricted immunoglobulin and is rarely reported in children.We characterized a series of nine pediatric patients from two academic centers with biopsy-proven PGNMID and additionally describe two patients with monotypic IgG in the setting of IgM deposition.Each patient presented with hematuria and/or proteinuria; however, only five had elevated serum creatinine. Prodromal or concurrent infection was identified in six patients, low C3 in five, and alternate complement pathway gene variants in two. No monoclonal serum proteins were identified in five tested patients. Seven patients had monotypic deposits composed of IgG3-λ, two showed IgG3-κ, and one each IgG1 and IgG3 with lambda dominance in the setting of IgM deposition. The glomerular pattern was predominantly mesangial proliferative or membranoproliferative glomerulonephritis (MPGN). Treatment and outcomes were variable; four patients have recent PGNMID diagnoses and therefore minimal follow up, one had relatively stable kidney function for over a decade, and six experienced kidney failure, with four receiving transplants. Recurrent deposits of the same isotype were identified in five of six transplanted kidneys, corresponding to three of four transplanted patients. One of these patients developed PGNMID recurrences in three separate kidney allografts over a 20-year disease course.Our study emphasizes the need for upfront IgG subclass investigation in pediatric mesangial or MPGN with IgG deposition and monotypic or biased light-chain staining. Furthermore, this pediatric experience suggests expanded pathogenic considerations in PGNMID. Graphical abstract.

    View details for DOI 10.1007/s00467-020-04763-5

    View details for PubMedID 33044675

  • Multicenter Clinicopathologic Correlation of Kidney Biopsies Performed in COVID-19 Patients Presenting With Acute Kidney Injury or Proteinuria. American journal of kidney diseases : the official journal of the National Kidney Foundation Akilesh, S. n., Nast, C. C., Yamashita, M. n., Henriksen, K. n., Charu, V. n., Troxell, M. L., Kambham, N. n., Bracamonte, E. n., Houghton, D. n., Ahmed, N. I., Chong, C. C., Thajudeen, B. n., Rehman, S. n., Khoury, F. n., Zuckerman, J. E., Gitomer, J. n., Raguram, P. C., Mujeeb, S. n., Schwarze, U. n., Shannon, M. B., De Castro, I. n., Alpers, C. E., Najafian, B. n., Nicosia, R. F., Andeen, N. K., Smith, K. D. 2020


    Kidney biopsy data inform us about pathologic processes associated with SARS CoV-2 infection. We conducted a multi-center evaluation of kidney biopsy findings in living patients to identify various kidney disease pathology in patients with COVID-19 and their association with SARS-CoV-2 infection.Case series.We identified 14 native and 3 transplant kidney biopsies performed for-cause in patients with documented recent or concurrent COVID-19 infection treated at 7 large hospital systems in the United States.Males and females were equally represented in our study cohort, with a higher proportion of Black (n=8) and Hispanic (n=5) patients. All 17 patients had RT-PCR confirmed COVID-19 infection, but only 3 presented with severe COVID-19 symptoms. Acute kidney injury (AKI; n=15) and proteinuria (n=11) were the most common indications for biopsy and these symptoms developed concurrently or within 1 week of COVID-19 symptoms in all patients. Acute tubular injury (n=14), collapsing glomerulopathy (n=7) and endothelial injury/thrombotic microangiopathy (n=6) were the most common histologic findings. Two of the three transplant patients developed active antibody-mediated rejection weeks after COVID-19 infection. Eight patients required dialysis, but others improved with conservative management.Small study size and short clinical follow up.Cases of even symptomatically mild COVID-19 infection were accompanied by AKI and/or heavy proteinuria that prompted a diagnostic kidney biopsy. While acute tubular injury was seen among the majority of them, uncommon pathology such as collapsing glomerulopathy and acute endothelial injury were detected, and most of these patients progressed to irreversible kidney injury and dialysis.

    View details for DOI 10.1053/j.ajkd.2020.10.001

    View details for PubMedID 33045255

  • Fibrillary Glomerulonephritis: Clinicopathologic Features and Atypical Cases from a Multi-Institutional Cohort CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Andeen, N. K., Troxell, M. L., Riazy, M., Avasare, R. S., Lapasia, J., Jefferson, J., Akilesh, S., Najafian, B., Nicosia, R. F., Alpers, C. E., Smith, K. D. 2019; 14 (12): 1741–50


    Fibrillary GN has been defined as an immune complex-mediated GN with amyloid-like fibrils larger than amyloid which are IgG positive and Congo red negative. With discovery of DNAJB9 as a highly sensitive and specific marker for fibrillary GN, the specificity of the morphologic criteria for establishing the diagnosis of fibrillary GN has come into question.We sought to (1) determine anatomic characteristics that best define fibrillary GN and (2) identify clinical and pathologic features that predict outcomes.We retrospectively reviewed kidney biopsies from patients diagnosed with fibrillary GN or suspected fibrillary GN between 1997 and 2017 (n=266, 65% female, median age 61). Approximately 11% of kidney biopsies had one or more unusual feature including monotypic deposits, Congo red positivity, or unusual fibril diameter. Fibrillary GN as a possible monoclonal gammopathy of renal significance represented <1% of cases. Immunostaining for DNAJB9 confirmed fibrillary GN in 100% of cases diagnosed as fibrillary GN and 79% of atypical cases diagnosed as possible fibrillary GN. At a median time of 24 months (interquartile range, 8-46 months) after biopsy (n=100), 53% of patients reached the combined primary outcome of ESKD or death, 18% had CKD, and 18% had partial remission. On multivariable analysis, male sex (adjusted hazard ratio [aHR], 3.82; 95% confidence interval [95% CI], 1.97 to 7.37) and eGFR were the most significant predictors of primary outcome (aHR of 8.02 if eGFR <30 ml/min per 1.73 m2 [95% CI, 1.85 to 34.75]; aHR of 6.44 if eGFR 30 to <45 ml/min per 1.73 m2 [95% CI, 1.38 to 29.99]). Immunosuppressive therapy with rituximab was significantly associated with stabilization of disease progression.Detection of DNAJB9 is a useful diagnostic tool for diagnosing atypical forms of fibrillary GN. The outcomes for fibrillary GN are poor and progression to ESKD is influenced predominantly by the degree of kidney insufficiency at the time of diagnosis and male sex. Rituximab may help preserve kidney function for select patients with fibrillary GN.This article contains a podcast at

    View details for DOI 10.2215/CJN.03870319

    View details for Web of Science ID 000506176900012

    View details for PubMedID 31685544

    View details for PubMedCentralID PMC6895488

  • A review of non-immune mediated kidney disease in systemic lupus erythematosus: A hypothetical model of putative risk factors. Seminars in arthritis and rheumatism Falasinnu, T., O'Shaughnessy, M. M., Troxell, M. L., Charu, V., Weisman, M. H., Simard, J. F. 2019


    About half of patients with systemic lupus erythematosus (SLE) are diagnosed with lupus nephritis (LN). Patients with SLE are also at increased risk for diabetes, hypertension and obesity, which together account for >70% of end-stage renal disease in the general population. The frequencies of non-LN related causes of kidney disease, and their contribution to kidney disease development and progression among patients with SLE have been inadequately studied. We hypothesize that a substantial, and increasing proportion of kidney pathology in patients with SLE might not directly relate to LN but instead might be explained by non-immune mediated factors such as diabetes, hypertension, and obesity. The goal of the manuscript is to draw attention to hypertension, diabetes and obesity as potential alternative causes of kidney damage in patients with SLE. Further, we suggest that misclassification of kidney disease etiology in patients with SLE might have important ramifications for clinical trial recruitment, epidemiologic investigation, and clinical care. Future studies aiming to elucidate and distinguish discrete causes of kidney disease - both clinically and histologically - among patients with SLE are desperately needed as improved understanding of disease mechanisms is paramount to advancing therapeutic discovery. Collaboration among rheumatologists, pathologists, nephrologists, and endocrinologists, and the availability of dedicated research funding, will be critical to the success of such efforts.

    View details for DOI 10.1016/j.semarthrit.2019.10.006

    View details for PubMedID 31866044

  • Rosai-Dorfman Disease of the Breast With Variable IgG4+ Plasma Cells: A Diagnostic Mimicker of Other Malignant and Reactive Entities. The American journal of surgical pathology Hoffmann, J. C., Lin, C., Bhattacharyya, S., Weinberg, O. K., Chisholm, K. M., Bayerl, M., Cascio, M., Venkataraman, G., Allison, K., Troxell, M., Chang, C., Bagg, A., George, T. I., O'Malley, D., Ohgami, R. S. 2019


    Rosai-Dorfman disease (RDD) is an uncommon disorder, characterized by an atypical expansion of histiocytes which classically shows emperipolesis and immunoreactivity with S-100 protein. RDD affects the lymph nodes as well as extranodal sites; however, RDD of the breast is exceptionally rare. Herein, we describe the histopathologic features of 22 cases of RDD occurring in the breast, with an emphasis on the differential diagnosis. All cases were notable for an exuberant lymphocytic infiltrate with and without germinal center formation, and the majority (19/22) showed numerous plasma cells: 5 to 132/high-power field (HPF). IgG and IgG4 immunohistochemical stains were available for 13 cases; in no instance were criteria for IgG4-related sclerosing disease met, though in a single case the IgG4/IgG ratio was increased to 25%. Sclerosis was present in the majority of cases (18/22), and was frequently prominent. RDD cells showing emperipolesis were present in all cases (22/22), and ranged from rare (<1/50HPF) to numerous (>50/50HPF). Two of the cases in our series were initially misdiagnosed as inflammatory myofibroblastic tumor and plasma cell mastitis with granulomatous inflammation. As emperipolesis can be indistinct, the presence of stromal fibrosis and a prominent lymphoplasmacytic inflammatory infiltrate should prompt a careful search for the characteristic histiocytes, which can be aided by the use of S-100 immunohistochemistry.

    View details for DOI 10.1097/PAS.0000000000001347

    View details for PubMedID 31436555

  • Ultrasound Assessment of Acute Kidney Injury ULTRASOUND QUARTERLY Kelahan, L. C., Desser, T. S., Troxell, M. L., Kamaya, A. 2019; 35 (2): 173–80
  • Collapsing glomerulopathy in older adults MODERN PATHOLOGY Kukull, B., Avasare, R. S., Smith, K. D., Houghton, D. C., Troxell, M. L., Andeen, N. K. 2019; 32 (4): 532–38
  • Predictive Markers Require Thorough Analytic Validation. Archives of pathology & laboratory medicine Troxell, M. L., Fulton, R. S., Swanson, P. E., Bellizzi, A. M., Fitzgibbons, P. L., Ambaye, A. B., Haas, T. S., Goldsmith, J. D., Loykasek, P. A., Miller, D. V., O'Malley, D. n., Qiu, J. n., Salama, M. E., Schaberg, K. B., Schwartz, R. A., Shia, J. n., Summers, T. A., Wu, Y. n. 2019; 143 (8): 907–9

    View details for DOI 10.5858/arpa.2019-0112-LE

    View details for PubMedID 31339757

  • Genomic landscape of ductal carcinoma in situ and association with progression. Breast cancer research and treatment Lin, C. Y., Vennam, S. n., Purington, N. n., Lin, E. n., Varma, S. n., Han, S. n., Desa, M. n., Seto, T. n., Wang, N. J., Stehr, H. n., Troxell, M. L., Kurian, A. W., West, R. B. 2019


    The detection rate of breast ductal carcinoma in situ (DCIS) has increased significantly, raising the concern that DCIS is overdiagnosed and overtreated. Therefore, there is an unmet clinical need to better predict the risk of progression among DCIS patients. Our hypothesis is that by combining molecular signatures with clinicopathologic features, we can elucidate the biology of breast cancer progression, and risk-stratify patients with DCIS.Targeted exon sequencing with a custom panel of 223 genes/regions was performed for 125 DCIS cases. Among them, 60 were from cases having concurrent or subsequent invasive breast cancer (IBC) (DCIS + IBC group), and 65 from cases with no IBC development over a median follow-up of 13 years (DCIS-only group). Copy number alterations in chromosome 1q32, 8q24, and 11q13 were analyzed using fluorescence in situ hybridization (FISH). Multivariable logistic regression models were fit to the outcome of DCIS progression to IBC as functions of demographic and clinical features.We observed recurrent variants of known IBC-related mutations, and the most commonly mutated genes in DCIS were PIK3CA (34.4%) and TP53 (18.4%). There was an inverse association between PIK3CA kinase domain mutations and progression (Odds Ratio [OR] 10.2, p < 0.05). Copy number variations in 1q32 and 8q24 were associated with progression (OR 9.3 and 46, respectively; both p < 0.05).PIK3CA kinase domain mutations and the absence of copy number gains in DCIS are protective against progression to IBC. These results may guide efforts to distinguish low-risk from high-risk DCIS.

    View details for DOI 10.1007/s10549-019-05401-x

    View details for PubMedID 31420779

  • Bladder cancer and its mimics: a sonographic pictorial review with CT/MR and histologic correlation. Abdominal radiology (New York) Wentland, A. L., Desser, T. S., Troxell, M. L., Kamaya, A. n. 2019


    Bladder cancer is the most common cancer of the urinary system and often presents with hematuria. Despite its relatively high incidence, bladder cancer is often under-recognized sonographically. Moreover, even when bladder abnormalities are identified, numerous other entities may mimic the appearance of bladder cancer. Given the incidence and prevalence of bladder cancer, it is important to recognize its variable appearance sonographically and distinguish it from its common mimics. We review the sonographic appearance of bladder cancer and its mimics, providing correlative CT/MR imaging as well as pathology. We stress the importance and advantage of ultrasound as a dynamic imaging modality, with the ability to optimize distinguishing bladder cancer from similar-appearing entities.

    View details for DOI 10.1007/s00261-019-02276-w

    View details for PubMedID 31676920

  • Kidney Biopsy Adequacy A Metric-based Study AMERICAN JOURNAL OF SURGICAL PATHOLOGY Ferrer, G., Andeen, N. K., Lockridge, J., Norman, D., Foster, B. R., Houghton, D. C., Troxell, M. L. 2019; 43 (1): 84–92


    There are differences in renal biopsy yield related to on-site evaluation, tissue division, and operator, among others. To understand these variations, we collected adequacy-associated data (%cortex, glomeruli, arteries, length) from consecutive native and allograft kidney biopsies over a 22-month period. In total, 1332 biopsies (native: 873, allograft: 459) were included, 617 obtained by nephrologists, 663 by radiologists, and 559 with access to on-site division. Proceduralists with access to on-site evaluation had significantly lower inadequacy rates and better division of tissue for light microscopy (LM), immunofluorescence, and electron microscopy than those without access to on-site evaluation. Radiologists in our region were significantly less likely to have access to on-site evaluation than nephrologists. On multivariate analysis for native kidney biopsies, the effect of having a radiologist perform the biopsy and having access to on-site division were both significant predictors of obtaining greater calculated amount of cortex for LM. Despite the trend for radiologists to obtain more tissue in general, biopsies from nephrologists contained a greater percentage of cortex and were more likely to be considered adequate for LM (native kidney inadequacy rate for LM: 1.11% vs. 5.41%, P=0.0086). Biopsies in which inadequate or marginal cortical tissue was submitted for LM had only minor decreases in the amount of cortex submitted for immunofluorescence and electron microscopy, revealing an opportunity for improved specimen triaging when limited tissue is obtained. In conclusion, both on-site evaluation/division and proceduralist significantly affect quantitative kidney biopsy metrics, which in turn affects the pathologist's ability to render an accurate diagnosis with appropriate prognostic information for the patient and treating nephrologist.

    View details for PubMedID 29877922

  • Methotrexate in the Treatment of Idiopathic Granulomatous Mastitis. The Journal of rheumatology Postolova, A. n., Troxell, M. L., Wapnir, I. L., Genovese, M. C. 2019


    Idiopathic granulomatous mastitis (IGM) is a disfiguring inflammatory breast disease without effective treatment. We report the largest IGM cohort treated with methotrexate monotherapy.Chart review was performed on patients evaluated by the Rheumatology Clinic, with histopathologically-established IGM, treated with methotrexate, and at least one follow up appointment.Nineteen female patients with an mean age of 33.5 years were identified. Most failed treatment with antibiotics, prednisone, and surgical intervention. By 15 months of treatment with methotrexate, 94% had disease improvement and 75% achieved disease remission.Methotrexate monotherapy is an effective treatment for IGM.

    View details for DOI 10.3899/jrheum.181205

    View details for PubMedID 31203215

  • A Case Report of Pediatric Clear Cell Carcinoma of the Urinary Bladder Associated With Polyomavirus AJSP-REVIEWS AND REPORTS Saleem, A., Brown, R. A., Higgins, J. T., Troxell, M. L., Kunder, C. A., Pinsky, B. A., Zambrano, E., Kao, C. 2018; 23 (6): 291–95
  • IgA-dominant glomerulonephritis with a membranoproliferative pattern of injury. Human pathology Andeen, N. K., Jefferson, J. A., Akilesh, S., Alpers, C. E., Bissonnette, M. L., Finn, L. S., Higgins, J., Houghton, D. C., Kambham, N., Magil, A., Najafian, B., Nicosia, R. F., Troxell, M. L., Smith, K. D. 2018; 81: 272–80


    Immunoglobulin A (IgA)-dominant membranoproliferative glomerulonephritis (MPGN) is a descriptive term for renal biopsies in which differential diagnoses of unusual IgA nephropathy (IgAN), infection-related GN, or other etiologies are considered. We sought to understand clinical and pathologic features of this finding. Native kidney biopsies with IgA-dominant immune deposits and diffuse MPGN features without significant exudative features or subepithelial deposits were retrospectively reviewed. Two groups (n = 27, 33 biopsies) were identified: patients with chronic liver disease and those without. Patients without chronic liver disease (n = 15) were men (73%, age 40) who presented with nephrotic-range proteinuria, hematuria, renal insufficiency, negative serologic studies, and no history of infection. At a median interval of 3 years, 11 had available follow-up information. Three (27%) progressed to end-stage renal disease. One had recurrent IgA-dominant GN in the renal allograft less than 1 year posttransplant. Four of 5 patients with repeat biopsies had persistent IgA-dominant MPGN. Patients with chronic liver disease (n = 12) had similar biopsy findings, but 42% had concurrent infections, some occult. At a median interval of 7 weeks, 8 patients (80% of those with follow-up) had died and 2 were dialysis dependent. In conclusion, IgA-dominant MPGN was seen in 2 clinical cohorts in this study. In patients without chronic liver disease, this appears to represent either a unique clinicopathologic entity with a poorer prognosis than IgAN or an aggressive variant of IgAN. Patients with chronic liver disease often have underlying infection, and regardless of treatment, die within 1 year because of complex medical conditions.

    View details for PubMedID 30420049

  • Thrombotic microangiopathy with intraglomerular IgM pseudothrombi in Waldenstrom macroglobulinemia and IgM monoclonal gammopathy. Journal of nephrology Tan, S. Y., Sibley, R. K., Belani, S., Iwasaki, S., Yankulin, L., Jonelis, T., Higgins, J. P., Kambham, N., Troxell, M. L. 2018


    IgM secreting myelomas or lymphomas, including Waldenstrom macroglobulinemia, are associated with a varied spectrum of renal pathology, including intracapillary hyaline deposits, cryoglobulin, membranoproliferative glomerulonephritis, amyloid, monoclonal immunoglobulin deposition disease, cast nephropathy, and lymphoma infiltration. We report our single institution experience, and describe five cases with distinctive glomerular pathology: intracapillary IgM pseudothrombi and thrombotic microangiopathic change, with glomerular intracellular crystals in two biopsies. Two patients were hypocomplementemic at presentation. This series adds to the recent literature on paraprotein associated thrombotic microangiopathy.

    View details for PubMedID 30334170

  • Collapsing glomerulopathy in older adults. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Kukull, B., Avasare, R. S., Smith, K. D., Houghton, D. C., Troxell, M. L., Andeen, N. K. 2018


    Collapsing glomerulopathy has been described in settings of viral infections, drug, genetic, ischemic, renal transplant, and idiopathic conditions. It has a worse prognosis than other morphologic variants of focal segmental glomerulosclerosis, and may be treated with aggressive immunosuppression. In this study, we sought to characterize the clinical and morphologic findings in older adults with collapsing glomerulopathy. Renal biopsies and associated clinical data from patients aged 65 or older with a diagnosis of collapsing glomerulopathy were retrospectively reviewed at 3 academic institutions. Patients (n=41, 61% male, median age 71) usually had hypertension (88%), nephrotic range proteinuria (91%), and renal insufficiency (median serum creatinine 2.5mg/dL). A likely precipitating drug (5%) or vascular procedure (5%) was identified in a minority of cases; viral infections were infrequent. Renal biopsies contained a median of 40% globally and 16% segmentally sclerotic glomeruli. Approximately 60% of cases had moderate or severe arteriosclerosis, arteriolar hyalinosis, and/or tubular atrophy and interstitial fibrosis; 7% had atheroembolic disease and 5% had thrombotic microangiopathy. In 28 patients with available follow-up information, eight (19%) were treated with immunosuppressives, which were not tolerated by 2. At a median interval of 14 months, 5 (18%) patients had died, 12 (43%) had end stage renal disease, and 12 were alive with renal insufficiency and proteinuria. Treatment with immunosuppressive therapy did not have a significant benefit with regard to the primary outcome of overall or renal survival. One steroid-treated patient with diabetes died 6 weeks after biopsy, with invasive rhinoorbital Rhizopus infection. In conclusion, collapsing glomerulopathy in older patients is usually not associated with viral infections, and is accompanied by significant chronic injury in glomeruli, vasculature, and tubulointerstitium. Aggressive immunosuppression likely contributed to one death in a patient with diabetes, and did not yield an overall or renal survival advantage in this cohort.

    View details for PubMedID 30327500

  • "Atrophic Kidney"-like Lesion: Clinicopathologic Series of 8 Cases Supporting a Benign Entity Distinct From Thyroid-like Follicular Carcinoma. The American journal of surgical pathology Herlitz, L., Hes, O., Michal, M., Tretiakova, M., Reyes-Mugica, M., Nguyen, J. K., Troxell, M. L., Przybycin, C. G., Magi-Galluzzi, C., McKenney, J. K. 2018


    Renal mass lesions with a follicular architecture resembling atrophic kidney have been described, but their distinction from thyroid-like follicular carcinoma of the kidney remains controversial. We collected 8 cases of this purported "atrophic kidney"-like lesion to fully describe their clinical and histologic spectrum, their possible etiology, and to discuss their distinction from other renal neoplasms. Eight total cases were identified with patient ages ranging from 9 to 48 years (mean: 29y; median: 28.5y). Four patients were female and 4 were male. The tumors were unifocal and size ranged from 1.6 to 4.9cm (mean: 3.4cm; median: 3.4cm). All 8 tumors had a remarkably similar histology. Each was enveloped by a smooth muscle rich capsule and had an overall low power "follicular" architecture. The luminal spaces of the "follicles" (or cysts) contained eosinophilic secretions and the lining epithelium was often flattened and atrophic, but some had more rounded cells with a distinctive hobnail arrangement. Many cysts contained discohesive round cells floating within the eosinophilic material, and some contained small intraluminal tufts with features of markedly atrophic glomeruli. Periodic acid-Schiff stains highlighted basement membrane material extending into these glomerular-like tufts, and some contained small distinct capillaries surrounded by endothelial cells, interspersed mesangial-like cells, and rare surrounding podocyte-like cells, providing additional evidence for glomerulocystic structures. Scattered calcifications were present within cysts (or within cyst walls) in varying numbers and were characterized by 2 types: psammoma body-like or more amorphous deposits. The tissue between cystic glomeruli contained predominantly small atrophic tubular structures, but collagenized stroma and smaller collapsed glomeruli were also present. The 2 tumors from the oldest 2 patients (48 and 39y) had a more striking degree of stromal hyalinization. Immunohistochemically, the cyst lining cells had a predominant WT-positive/PAX-8 negative/CK7-negative phenotype, while tubules were typically WT-1 negative/PAX-8 positive/CK7-positive. Upon comparison to a control group of 10 kidneys containing incidental non-mass-forming glomerulocystic change, the morphologic features and immunophenotype were identical. To date, no patient has had any recurrence or aggressive clinical behavior based on follow status in 7 of 8 cases (follow-up range: 9 to 168mo; median: 24mo; mean: 40mo). In summary, we describe the clinicopathologic features of 8 unique, benign "atrophic kidney"-like lesions that may simply represent a non-neoplastic form of organizing tubular atrophy and glomerulocystic change, and emphasize their distinction from thyroid-like follicular carcinoma of the kidney.

    View details for PubMedID 30285996

  • Ultrasound Assessment of Acute Kidney Injury. Ultrasound quarterly Kelahan, L. C., Desser, T. S., Troxell, M. L., Kamaya, A. n. 2018


    Ultrasound assessment of the kidneys in patients with renal impairment has been described in various ways in the critical care, nephrology, and radiology literature, resulting in a somewhat heterogeneous picture of the gray-scale and Doppler ultrasound manifestation of acute kidney injury (AKI). Given that ultrasound assessment can potentially identify reversible causes of AKI or identify underlying chronic kidney disease, it is important for radiologists to be aware of the common etiologies of AKI and the spectrum of ultrasound findings. We review the definition and etiologies of renal injury and introduce the ultrasound SERVeillance framework-assessment of renal size, echogenicity, renal hilum, and vascularity-for the imaging assessment of AKI.

    View details for PubMedID 30300324

  • Comparison of Estrogen and Progesterone Receptor Antibody Reagents Using Proficiency Testing Data ARCHIVES OF PATHOLOGY & LABORATORY MEDICINE Troxell, M. L., Long, T., Hornick, J. L., Ambaye, A. B., Jensen, K. C. 2017; 141 (10): 1402–12


    - Immunohistochemical analysis of estrogen receptor (ER) and progesterone receptor (PgR) expression in breast cancer is the current standard of care and directly determines therapy. In 2010 the American Society of Clinical Oncology and the College of American Pathologists (ASCO/CAP) published guidelines for ER and PgR predictive testing, encompassing preanalytic, analytic, postanalytic factors; antibody validation; and proficiency testing.- To compare the performance of different antibody reagents for ER and PgR immunohistochemical analysis by using CAP proficiency testing data.- The CAP PM2 survey uses tissue microarrays of ten 2-mm cores per slide. We analyzed survey data from 80 ER and 80 PgR cores by antibody clone from more than 1200 laboratories.- Laboratories used the ER antibodies SP1 (72%), 6F11 (17%), 1D5 (3%), and the PgR antibodies 1E2 (61%), 16 (12%), PgR-636 (13%), PgR-1294 (8%) in 2015. While 63 of 80 ER cores (79%) were scored similarly using each of the 3 antibodies, there were significant differences for others, with SP1 yielding more positive interpretations. Four cores were scored as ER negative by more than half of the laboratories using 1D5 or 6F11, while SP1 produced positive results in more than 70% of laboratories using that antibody. Despite the greater variety of PgR antibody reagents and greater PgR tumor heterogeneity, 61 of 80 cores (76%) were scored similarly across the 4 PgR antibodies.- Accurate ER and PgR testing in breast cancer is crucial for appropriate treatment. The CAP proficiency testing data demonstrate differences in staining results by ER clone, with SP1 yielding more positive results.

    View details for DOI 10.5858/arpa.2016-0497-OA

    View details for Web of Science ID 000417030000010

    View details for PubMedID 28714765

  • Merkel cell carcinoma, melanoma, metastatic mimics of breast cancer SEMINARS IN DIAGNOSTIC PATHOLOGY Troxell, M. L. 2017; 34 (5): 479–95


    Merkel cell carcinoma and melanoma can each occur primarily in breast skin, or metastasize to the breast. The breast is a rare site of metastasis of essentially any and every type of tumor, including carcinomas, sarcomas, and hematolymphoid neoplasms, and 10-30% of breast metastases may represent the initial presentation of disease. Although metastases generally recapitulate histologic features of the primary tumor, they are diagnostically challenging given their rarity and morphologic overlap with breast carcinoma, including special types of breast cancer. Histologic clues may include lack of carcinoma in situ, lack of central elastosis, pattern of infiltration around normal breast structures, yet none of these are specific. Careful correlation with clinical history and judicious use of immunostain panels is essential in approaching these cases.

    View details for PubMedID 28645508

  • TdT-positive Infiltrate in Inflamed Pediatric Kidney: A Potential Diagnostic Pitfall. American journal of surgical pathology Dunlap, J. B., Cascio, M. J., Stacey, X., Click, S., Troxell, M. L. 2017


    We encountered a patient with infantile nephrotic syndrome associated with a dense interstitial inflammatory infiltrate and prominent extramedullary hematopoiesis. Immunohistochemical analysis revealed numerous terminal deoxynucleotidyl transferase (TdT)-positive cells, which may raise concern for lymphoblastic lymphoma. Thus, we further characterized a group of pediatric kidneys with inflammation. TdT-positive nuclei were quantitated, and dual immunostains for TdT/CD79a, TdT/CD3, and TdT/CD43 were performed in a subset of cases; flow cytometry was performed in 1 case. TdT-positive nuclei were present in inflamed pediatric kidneys in 40 of 42 patients. TdT counts (average of 3 maximal high-power fields) ranged from 1 to >200, with a mean of 47. The presence and number of TdT-positive nuclei showed a strong association with younger patient age. Extramedullary hematopoiesis was identified in 11/42 patients, all under the age of 1. The presence of extramedullary hematopoiesis did not correlate with TdT count (P=0.158). Dual immunostaining and flow cytometric analysis in 1 case showed weak expression of B-cell markers and favored normal precursor B cells. Although TdT is a common marker of lymphoblastic lymphoma, we have demonstrated that TdT-positive cells may be part of the inflammatory milieu in infant kidneys. Together with cytologic, architectural, and clinical features, these data can help to avoid misinterpretation of involvement by lymphoblastic lymphoma/leukemia.

    View details for DOI 10.1097/PAS.0000000000000828

    View details for PubMedID 28248816

  • 'Non-classical' HER2 FISH results in breast cancer: a multi-institutional study MODERN PATHOLOGY Ballard, M., Jalikis, F., Krings, G., Schmidt, R. A., Chen, Y., Rendi, M. H., Dintzis, S. M., Jensen, K. C., West, R. B., Sibley, R. K., Troxell, M. L., Allison, K. H. 2017; 30 (2): 227-235


    The 2013 CAP/ASCO HER2 Testing Guidelines Update modified HER2 FISH categories such that some cases with 'monosomy', 'co-amplification/polysomy', low-level increased HER2 signals or clustered heterogeneity now are considered amplified or equivocal. This study examines the frequency and clinico-pathologic characteristics of breast cancers with equivocal or 'non-classical' HER2 FISH results. Breast cancers (2001-2014) with HER2 FISH results, HER2 immunohistochemistry, ER, grade, and age from three institutions (Stanford, UCSF, UWMC) were collected. HER2 FISH was interpreted using the updated recommendations. Amplified cases with non-classical results were grouped into the following categories: (1) 'monosomy' (ratio ≥2.0, mean HER2/cell<4.0); (2) 'co-amplified' (ratio<2.0, mean HER2/cell ≥6.0); (3) 'low amplified' (ratio ≥2.0, mean HER2/cell 4.0-5.9). Heterogeneous cases with clustered HER2-positive cells were also included. Of 8068 cases, 5.2% were equivocal and 4.6% had a 'non-classical' HER2 amplified result; 1.4% 'monosomy', 0.8% 'co-amplified', 2.1% 'low amplified', and 0.3% clustered heterogeneity. These cancers had a high frequency of ER positive (80.4%), Nottingham grade 3 (52.1%) results. The highest percentage of grade 3 cancers (66.7%) and positive HER2 immunohistochemistry (31.7%) was in the 'co-amplified' group. The 'monosomy' group had the highest percent grade 1 cancers (13.3%) and was most frequently HER2 immunohistochemistry negative (30.1%). Equivocal cases had very similar characteristics to the 'low-amplified' category. Cases with non-classical HER2 amplification or equivocal results are typically ER positive, higher grade cancers. 'Co-amplified' cases have the highest frequencies of aggressive characteristics and 'monosomy' cases the highest frequencies of lower risk features. With little clinical outcomes data currently available on these non-classical HER2 results, these results support the current classification scheme for HER2 FISH, with case-by-case correlation with additional clinical-pathologic factors when evaluating whether to offer HER2-targeted therapies in these non-classical cases.Modern Pathology advance online publication, 14 October 2016; doi:10.1038/modpathol.2016.175.

    View details for DOI 10.1038/modpathol.2016.175

    View details for Web of Science ID 000393257400007

  • HER2 Testing and Clinical Decision Making in Gastroesophageal Adenocarcinoma Guideline From the College of American Pathologists, American Society for Clinical Pathology, and American Society of Clinical Oncology ARCHIVES OF PATHOLOGY & LABORATORY MEDICINE Bartley, A. N., Washington, M. K., Ventura, C. B., Ismaila, N., Colasacco, C., Benson, A. B., Carrato, A., Gulley, M. L., Jain, D., Kakar, S., Mackay, H. J., Streutker, C., Tang, L., Troxell, M., Ajani, J. A. 2016; 140 (12): 1345-1363


    - ERBB2 (erb-b2 receptor tyrosine kinase 2 or HER2) is currently the only biomarker established for selection of a specific therapy for patients with advanced gastroesophageal adenocarcinoma (GEA). However, there are no comprehensive guidelines for the assessment of HER2 in patients with GEA.- To establish an evidence-based guideline for HER2 testing in patients with GEA, to formalize the algorithms for methods to improve the accuracy of HER2 testing while addressing which patients and tumor specimens are appropriate, and to provide guidance on clinical decision making.- The College of American Pathologists, American Society for Clinical Pathology, and American Society of Clinical Oncology convened an expert panel to conduct a systematic review of the literature to develop an evidence-based guideline with recommendations for optimal HER2 testing in patients with GEA.- The panel is proposing 11 recommendations with strong agreement from the open-comment participants.- The panel recommends that tumor specimen(s) from all patients with advanced GEA, who are candidates for HER2-targeted therapy, should be assessed for HER2 status before the initiation of HER2-targeted therapy. Clinicians should offer combination chemotherapy and a HER2-targeted agent as initial therapy for all patients with HER2-positive advanced GEA. For pathologists, guidance is provided for morphologic selection of neoplastic tissue, testing algorithms, scoring methods, interpretation and reporting of results, and laboratory quality assurance.- This guideline provides specific recommendations for assessment of HER2 in patients with advanced GEA while addressing pertinent technical issues and clinical implications of the results.

    View details for DOI 10.5858/arpa.2016-0331-CP.s1

    View details for Web of Science ID 000390371400007

    View details for PubMedID 27841667

  • Renal cell carcinoma in kidney allografts: histologic types, including biphasic papillary carcinoma. Human pathology Troxell, M. L., Higgins, J. P. 2016; 57: 28-36


    Kidney transplant recipients are at increased risk for malignancy, with about 5% incidence of cancer in native end-stage kidneys. Carcinoma in the renal allograft is far less common. Prior studies have demonstrated a propensity for renal cell carcinomas (RCCs) of papillary subtypes in end-stage kidneys, and perhaps in allograft kidneys, but most allograft studies lack detailed pathologic review and predate the current classification system. We reviewed our experience with renal carcinoma in kidney allografts at 2 academic centers applying the International Society of Urological Pathology classification, informed by immunohistochemistry. The incidence of renal allograft carcinoma was about 0.26% in our population. Of 12 allograft carcinomas, 6 were papillary (50%), 4 were clear cell (33%), 1 was clear cell (tubulo)papillary, and 1 chromophobe. Two of the papillary carcinomas had distinctive biphasic glomeruloid architecture matching the newly named "biphasic squamoid alveolar" pattern and were difficult to classify on core biopsies. The 2 cell types had different immunophenotypes in our hands (eosinophilic cells: RCC-/CK34betaE12+ weight keratin +/cyclin D1+; clear cells: RCC+/cytokeratin high molecular weight negative to weak/cyclin D1-). None of the patients experienced cancer recurrences or metastasis. Our study confirms the predilection for papillary RCCs in kidney allografts and highlights the occurrence of rare morphologic variants. Larger studies are needed with careful pathologic review, which has been lacking in the literature.

    View details for DOI 10.1016/j.humpath.2016.06.018

    View details for PubMedID 27396934

  • Multiplexed imaging reveals heterogeneity of PI3K/MAPK network signaling in breast lesions of known PIK3CA genotype. Breast cancer research and treatment Jacob, T., Gray, J. W., Troxell, M., Vu, T. Q. 2016; 159 (3): 575-583


    Activating genetic changes in the phosphatidylinositol-3-kinase (PI3K) signaling pathway are found in over half of invasive breast cancers (IBCs). Previously, we discovered numerous hotspot PIK3CA mutations in proliferative breast lesions. Here, we investigate the spatial nature of PI3K pathway signaling and its relationship with PI3K genotype in breast lesions.We identified PI3K phosphosignaling network signatures in columnar cell change (CCL), usual ductal hyperplasia (UDH), ductal carcinoma in situ (DCIS), and IBC in 26 lesions of known PIK3CA genotype from 10 human breast specimens using a hyperspectral-based multiplexed tissue imaging platform (MTIP) to simultaneously quantitate PI3K/MAPK pathway targets (pAKT473, pAKT308, pPRAS40, pS6, and pERK) in FFPE tissue, with single-cell resolution.We found that breast lesional epithelia contained spatially heterogeneous patterns of PI3K pathway phosphoprotein signatures, even within microscopic areas of CCL, UDH, DCIS, and IBC. Most lesions contained 3-12 unique phosphoprotein signatures within the same microscopic field. The dominant phosphoprotein signature for each lesion was not well correlated with lesion genotype or lesion histology, yet samples from the same patient tended to group together. Further, 5 UDH/CCL lesions across different patients had a common phosphosignature at the epithelial-stromal interface (possible myoepithelial cells) that was distinct from both the adjacent lesional epithelium and distinct from adjacent stroma.We present the first spatial mapping of PI3K phosphoprotein networks in proliferative breast lesions and demonstrate complex PI3K signaling heterogeneity that defies simple correlation between PIK3CA genotype and phosphosignal pattern.

    View details for DOI 10.1007/s10549-016-3962-1

    View details for PubMedID 27581127

  • Practical Applications in Immunohistochemistry Evaluation of Rejection and Infection in Organ Transplantation ARCHIVES OF PATHOLOGY & LABORATORY MEDICINE Troxell, M. L., Lanciault, C. 2016; 140 (9): 910-925


    Context .- Immunohistochemical analysis of tissue biopsy specimens is a crucial tool in diagnosis of both rejection and infection in patients with solid organ transplants. In the past 15 years, the concept of antibody-mediated rejection has been refined, and diagnostic criteria have been codified in renal, heart, pancreas, and lung allografts (with studies ongoing in liver, small intestine, and composite grafts), all of which include immunoanalysis for the complement split product C4d. Objectives .- To review the general concepts of C4d biology and immunoanalysis, followed by organ-allograft-specific data, and interpretative nuances for kidney, pancreas, and heart, with discussion of early literature for lung and liver biopsies. Additionally, practical applications and limitations of immunostains for infectious organisms (Polyomavirus, Adenoviridae (adenovirus), and the herpes virus family, including Herpes simplex virus, Cytomegalovirus, Human herpes virus 8, and Epstein-Barr virus) are reviewed in the context of transplant recipients. Data Sources .- Our experience and published primary and review literature. Conclusions .- Immunohistochemistry continues to have an important role in transplant pathology, most notably C4d staining in assessment of antibody-mediated rejection and assessment of viral pathogens in tissue. In all facets of transplant pathology, correlation of morphology with special studies and clinical data is critical, as is close communication with the transplant team.

    View details for DOI 10.5858/arpa.2015-0275-CP

    View details for PubMedID 26759930

  • Myoepithelial cells in lobular carcinoma in situ: distribution and immunophenotype. Human pathology Wang, Y., Jindal, S., Martel, M., Wu, Y., Schedin, P., Troxell, M. 2016; 55: 126-134


    Myoepithelial cells have important physical and paracrine roles in breast tissue development, maintenance, and tumor suppression. Recent molecular and immunohistochemical studies have demonstrated phenotypic alterations in ductal carcinoma in situ-associated myoepithelial cells. Although the relationship of lobular carcinoma in situ (LCIS) and myoepithelial cells was described in 1980, further characterization of LCIS-associated myoepithelial cells is lacking. We stained 27 breast specimens harboring abundant LCIS with antibodies to smooth muscle myosin heavy chain, smooth muscle actin, and calponin. Dual stains for E-cadherin/smooth muscle myosin heavy chain and CK7/p63 were also performed. In each case, the intensity and distribution of staining in LCIS-associated myoepithelial cells were compared with normal breast tissue on the same slide. In 78% of the cases, LCIS-associated myoepithelial cells demonstrated decreased staining intensity for one or more myoepithelial markers. The normal localization of myoepithelial cells (flat against the basement membrane, pattern N) was seen in 96% of LCIS, yet 85% of cases had areas with myoepithelial cell cytoplasm oriented perpendicular to the basement membrane (pattern P), and in 30% of cases, myoepithelial cells appeared focally admixed with LCIS cells (pattern C). This study characterizes detailed architectural and immunophenotypic alterations of LCIS-associated myoepithelial cells. The finding of variably diminished staining favors application of several myoepithelial immunostains in clinical practice. The interaction of LCIS with myoepithelial cells, especially in light of the perpendicular and central architectural arrangements, deserves further mechanistic investigation.

    View details for DOI 10.1016/j.humpath.2016.05.003

    View details for PubMedID 27195907

  • Antineoplastic Treatment and Renal Injury: An Update on Renal Pathology Due to Cytotoxic and Targeted Therapies. Advances in anatomic pathology Troxell, M. L., Higgins, J. P., Kambham, N. 2016; 23 (5): 310-329


    Cancer patients experience kidney injury from multiple sources, including the tumor itself, diagnostic procedures, hypovolemia, infection, and drug exposure, superimposed upon baseline chronic damage. This review will focus on cytotoxic or targeted chemotherapy-associated renal injury. In this setting, tubulointerstitial injury and thrombotic microangiopathy (vascular injury) are more common than other forms of kidney injury including glomerular. Cisplatin, pemetrexed, and ifosfamide are well-known causes of acute tubular injury/necrosis. Acute interstitial nephritis seems underrecognized in this clinical setting. Interstitial nephritis is emerging as an "immune-related adverse effect" (irAE's) with immune checkpoint inhibitors in small numbers of patients. Acute kidney injury is rarely reported with targeted therapies such as BRAF inhibitors (vemurafinib, dabrafenib), ALK inhibitors (crizotinib), and mTOR inhibitors (everolimus, temsirolimus), but additional biopsy data are needed. Tyrosine kinase inhibitors and monoclonal antibodies that block the vascular endothelial growth factor pathway are most commonly associated with thrombotic microangiopathy. Other causes of thrombotic microangiopathy in the cancer patients include cytotoxic chemotherapies such as gemcitabine and mitomycin C, hematopoietic stem cell transplant, and cancer itself (usually high-stage adenocarcinoma with marrow and vascular invasion). Cancer patients are historically underbiopsied, but biopsy can reveal type, acuity, and chronicity of renal injury, and facilitate decisions concerning continuation of chemotherapy and/or initiation of renoprotective therapy. Biopsy may also reveal unrelated and unanticipated findings in need of treatment.

    View details for DOI 10.1097/PAP.0000000000000122

    View details for PubMedID 27403615

  • Allograft pancreas: pale acinar nodules HUMAN PATHOLOGY Troxell, M. L., Drachenberg, C. 2016; 54: 127-133


    Microscopic pale-staining acinar nodules were characterized in native pancreas in the 1980s under a variety of names but have been infrequently reported since. We retrospectively studied the frequency and characteristics of pale acinar nodules in allograft pancreas biopsies, as compared to a sampling of native pancreas specimens at our center. Pale acinar nodules were present in 13% (9/69) of allograft biopsies from 22% (7/32) of transplant patients, and 23% (5/22) of native pancreas surgical specimens, although more nodules per pancreas area were present in allograft needle biopsies. Acinar nodules had size of 100 to 700 μm, were periodic acid-Schiff pale, were synaptophysin negative, stained more weakly with keratin CAM 5.2 compared to surrounding parenchyma, and had a low proliferative rate. Ultrastructural evaluation revealed paucity of zymogen granules with dilated cistern-like structures. In our experience, pale acinar nodules have similar features in allograft and native pancreas specimens, yet remain of uncertain etiology and significance.

    View details for DOI 10.1016/j.humpath.2016.02.029

    View details for PubMedID 27063474

  • Renal pathology in hematopoietic cell transplant recipients: a contemporary biopsy, nephrectomy, and autopsy series MODERN PATHOLOGY Brinkerhoff, B. T., Houghton, D. C., Troxell, M. L. 2016; 29 (6): 637-652


    Renal injury in hematopoietic cell transplant recipients may be related to a combination of factors including chemotherapy, radiation, infection, immunosuppressive agents, ischemia, and graft-versus-host disease, and can involve glomerular, tubulointerstitial, and vascular structures. We reviewed renal pathology from 67 patients at a single institution (2009-2014), including 14 patients with biopsy for clinical dysfunction, 6 patients with surgical kidney resection for other causes, and 47 autopsy patients. Kidney specimens frequently contained multiple histopathologic abnormalities. Thrombotic microangiopathy, membranous nephropathy, minimal change disease, and focal segmental glomerulosclerosis were the most common glomerular findings. Pathologies not previously reported in the hematopoietic cell transplant setting included collapsing glomerulopathy, antiglomerular basement membrane disease, fibrillary glomerulonephritis, and in the case of two surgical resections distinctive cellular segmental glomerular lesions that defied classification. Kidney specimens frequently demonstrated acute tubular injury, interstitial fibrosis, arteriolar hyaline, and arteriosclerosis. Other kidney findings at autopsy included leukemia and amyloid (both recurrent), diabetic nephropathy, bacterial infection, fungal invasion, and silver deposition along glomerular and tubular basement membranes. Also in the autopsy cohort, C4d immunohistochemistry demonstrated unexpected membranous nephropathy in two patients, yet C4d also colocalized with arteriolar hyaline. This retrospective hematopoietic cell transplant cohort illustrates multifaceted renal injury in patients with renal dysfunction, as well as in patients without clinically recognized kidney injury.Modern Pathology advance online publication, 25 March 2016; doi:10.1038/modpathol.2016.61.

    View details for DOI 10.1038/modpathol.2016.61

    View details for PubMedID 27015134

  • Cystic Neutrophilic Granulomatous Mastitis Association With Gram-Positive Bacilli and Corynebacterium AMERICAN JOURNAL OF CLINICAL PATHOLOGY Troxell, M. L., Gordon, N. T., Doggett, J. S., Ballard, M., Vetto, J. T., Pommier, R. F., Naik, A. M. 2016; 145 (5): 635-645


    To determine whether cystic neutrophilic granulomatous mastitis (CNGM) can be associated with Gram-positive bacilli and CorynebacteriumWe reviewed our experience with 35 granulomatous mastitis patients over a 10-year period, including histologic pattern, Gram stain and other microbiologic data, clinical presentation, treatment and outcome.Biopsies from 19 patients demonstrated CNGM, while 16 patients had other patterns of granulomatous mastitis. Gram-positive organisms were seen within microcystic spaces in 16/19 CNGM, but 0/16 non-CNGM patients (P = .000). Culture or molecular studies demonstrated Corynebacterium species in three, all CNGM. Patients with CNGM were more likely to be younger, of Hispanic ethnicity, and born outside of the United States. Granulomatous mastitis resolved after a protracted course with widely variable treatment (antibiotics, surgery, steroids).Our data further support CNGM as an infectious disease; further study of Corynebacterium-directed therapy in CNGM is needed.

    View details for DOI 10.1093/AJCP/AQW046

    View details for PubMedID 27247368

  • Atypical anti-glomerular basement membrane disease. Clinical kidney journal Troxell, M. L., Houghton, D. C. 2016; 9 (2): 211-221


    Anti-glomerular basement membrane (anti-GBM) disease classically presents with aggressive necrotizing and crescentic glomerulonephritis, often with pulmonary hemorrhage. The pathologic hallmark is linear staining of GBMs for deposited immunoglobulin G (IgG), usually accompanied by serum autoantibodies to the collagen IV alpha-3 constituents of GBMs.Renal pathology files were searched for cases with linear anti-GBM to identify cases with atypical or indolent course. Histopathology, laboratory studies, treatment and outcome of those cases was reviewed in detail.Five anti-GBM cases with atypical clinicopathologic features were identified (accounting for ∼8% of anti-GBM cases in our laboratory). Kidney biopsies showed minimal glomerular changes by light microscopy; one patient had monoclonal IgG deposits in an allograft (likely recurrent). Three patients did not have detectable serum anti-GBM by conventional assays. Three patients had indolent clinical courses after immunosuppressive treatment. One patient, untreated after presenting with brief mild hematuria, re-presented after a short interval with necrotizing and crescentic glomerulonephritis.Thorough clinicopathologic characterization and close follow-up of patients with findings of atypical anti-GBM on renal biopsy are needed. Review of the literature reveals only rare well-documented atypical anti-GBM cases to date, only one of which progressed to end-stage kidney disease.

    View details for DOI 10.1093/ckj/sfv140

    View details for PubMedID 26985371

  • Polyomavirus large T antigen is prevalent in urothelial carcinoma post-kidney transplant HUMAN PATHOLOGY Yan, L., Salama, M. E., Lanciault, C., Matsumura, L., Troxell, M. L. 2016; 48: 122-131


    Viral pathogens have been associated with both infectious disease and neoplasia in transplant recipients. Polyomavirus is emerging as a potential causative agent for genitourinary tract cancer in post-kidney transplant patients. Human papillomavirus (HPV) has a proven role in squamous cancers, but has not been studied in genitourinary malignancies in transplantation. Of 2345 kidney transplants performed at our center over the past 20 years, we identified 16 patients with 20 genitourinary cancers (0.7%), including 13 bladder/ureter carcinomas, 5 renal cell carcinomas (RCCs), and 2 prostate carcinomas. We performed immunohistochemical staining for polyomavirus large T antigen and p16, followed by in situ hybridization for HPV in p16+ cases. Four cases of high-grade invasive urothelial bladder carcinomas were positive for large T. Large T+ urothelial carcinomas developed at least 8 years posttransplant in young men, 3 with history of BK polyoma viremia, 2 of whom had native kidney failure due to reflux/obstruction. In situ hybridization for high-risk HPV was negative in all tested cases. Overall, 3 patients died of carcinoma. All 5 RCCs were negative for both large T and p16; 2 prostate cancers were p16 negative and p16+/HPV negative, respectively. Thus, our study shows a relatively high prevalence of large T antigen in urothelial carcinoma in kidney transplant patients (31%), but not in RCC. Although sample size is small, young patients with obstructive disease may be at particular risk for developing large T-positive urothelial carcinoma. Overall, our data further support the necessities of long-term cancer surveillance for renal transplant patients.

    View details for DOI 10.1016/j.humpath.2015.09.021

    View details for PubMedID 26615524

  • Myoepithelial Cell Differentiation Markers in Ductal Carcinoma in Situ Progression AMERICAN JOURNAL OF PATHOLOGY Russell, T. D., Jindal, S., Agunbiade, S., Gao, D., Troxell, M., Borges, V. F., Schedin, P. 2015; 185 (11): 3076-3089


    We describe a preclinical model that investigates progression of early-stage ductal carcinoma in situ (DCIS) and report that compromised myoepithelial cell differentiation occurs before transition to invasive disease. Human breast cancer cells were delivered into the mouse mammary teat by intraductal injection in the absence of surgical manipulations and accompanying wound-healing confounders. DCIS-like lesions developed throughout the mammary ducts with full representation of human DCIS histologic patterns. Tumor cells were incorporated into the normal mammary epithelium, developed ductal intraepithelial neoplasia and DCIS, and progressed to invasive carcinoma, suggesting the model provides a rigorous approach to study early stages of breast cancer progression. Mammary glands were evaluated for myoepithelium integrity with immunohistochemical assays. Progressive loss of the myoepithelial cell differentiation markers p63, calponin, and α-smooth muscle actin was observed in the mouse myoepithelium surrounding DCIS-involved ducts. p63 loss was an early indicator, calponin loss intermediate, and α-smooth muscle actin a later indicator of compromised myoepithelium. Loss of myoepithelial calponin was specifically associated with gain of the basal marker p63 in adjacent tumor cells. In single time point biopsies obtained from 16 women diagnosed with pure DCIS, a similar loss in myoepithelial cell markers was observed. These results suggest that further research is warranted into the role of myoepithelial cell p63 and calponin expression on DCIS progression to invasive disease.

    View details for DOI 10.1016/j.ajpath.2015.07.004

    View details for PubMedID 26343330

  • The New Equivocal Changes to HER2 FISH Results When Applying the 2013 ASCO/CAP Guidelines AMERICAN JOURNAL OF CLINICAL PATHOLOGY Long, T. H., Lawce, H., Durum, C., Moore, S. R., Olson, S. B., Gatter, K., Troxell, M. L. 2015; 144 (2): 253-262


    Human epidermal growth factor receptor 2 (HER2, ERBB2) testing is an important prognostic/predictive marker in breast cancer management, especially in selecting HER2-targeted treatment. American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines address HER2 status and were recently revised in 2013, replacing the 2007 version. For in situ hybridization interpretation, 2013 guidelines return to the prior threshold of a HER2/CEP17 ratio of 2.0 or greater for positive and eliminate 1.8 to 2.2 as the equivocal range. Also, the HER2 signal/nucleus ratio is accounted for, with 6.0 or greater for positive and 4.0 to less than 6.0 for equivocal, even in cases with a HER2/CEP17 ratio less than 2.0.With institutional review board approval, we reviewed our 2006 to 2012 HER2 fluorescence in situ hybridization (FISH) results and classified them according to both the 2007 and 2013 guidelines as negative, positive, or equivocal.Of 717 HER2 FISH results, 55 (7.7%) changed category when reassessed by 2013 guidelines. Nineteen of 25 results in the 2007 equivocal category were reassigned as positive (n = 13) or negative (n = 6). Thirty-five previously negative cases became equivocal in the 2013 scheme, 12 of these with 1+ immunohistochemistry. The positive category increased from 71 to 85.The 2013 ASCO/CAP guidelines increased the number of HER2 FISH positive and equivocal results. The equivocal group is substantially different, posing a dilemma for clinical management.

    View details for DOI 10.1309/AJCP3Q9WFOQTKUVV

    View details for PubMedID 26185310

  • Glomerular Endothelial Vesicles in a Renal Allograft An Unusual Pattern of Immunoglobulin Deposition in a Patient With Biclonal Gammopathy of Unknown Significance AMERICAN JOURNAL OF SURGICAL PATHOLOGY Flatley, E. M., Segal, G. M., Batiuk, T. D., Bennett, W. M., Houghton, D. C., Troxell, M. L. 2015; 39 (6): 864-869


    Paraproteins have varied effects on the kidney on the basis of molecular structure, concentration, and renal function. Prototypical patterns include myeloma cast nephropathy, monoclonal immunoglobulin deposition disease, and amyloid, among others. We report a 69-year-old man with end-stage diabetic nephropathy and biclonal gammopathy of unknown significance. Serum monoclonal immunoglobulin G (IgG)-κ and urine monoclonal free λ light chains were identified during workup for nephrotic syndrome. A native renal biopsy demonstrated diabetic nephropathy, without indication of paraprotein-related pathology. After transplantation, a surveillance biopsy showed endothelialitis (type 2 rejection) and abundant eosinophilic droplets, nearly occluding glomerular capillary loops. Electron microscopy localized tightly packed electron-dense vesicles in glomerular endothelial cells. Immunofluorescence studies revealed IgG-κ-dominant endothelial staining, along with λ monotypic protein resorption droplets in tubules. Two additional biopsies within the following year showed this same paraprotein distribution, with some increase in mesangial sclerosis. Two years after transplant the patient remains asymptomatic with normal creatinine levels. Literature review yields rare cases of immunoglobulin crystalline deposits in multiple glomerular cell types, rarely including endothelial cells; however, this appears to be the first report of monoclonal immunoglobulin vesicles localized solely to endothelial cells. As these vesicles were not seen in the native kidney biopsy, we hypothesize an interaction of alloimmune-mediated endothelial injury and the physiochemical properties of the IgG-κ paraprotein. In addition, this case illustrates simultaneous different patterns of accumulation of monoclonal immunoglobulin and light chain components in this unique patient with biclonal gammopathy of unknown significance.

    View details for PubMedID 25723111

  • Novel mutations in neuroendocrine carcinoma of the breast: possible therapeutic targets. Applied immunohistochemistry & molecular morphology Ang, D., Ballard, M., Beadling, C., Warrick, A., Schilling, A., O'Gara, R., Pukay, M., Neff, T. L., West, R. B., Corless, C. L., Troxell, M. L. 2015; 23 (2): 97-103


    Primary neuroendocrine carcinoma of the breast is a rare variant, accounting for only 2% to 5% of diagnosed breast cancers, and may have relatively aggressive behavior. Mutational profiling of invasive ductal breast cancers has yielded potential targets for directed cancer therapy, yet most studies have not included neuroendocrine carcinomas. In a tissue microarray screen, we found a 2.4% prevalence (9/372) of neuroendocrine breast carcinoma, including several with lobular morphology. We then screened primary or metastatic neuroendocrine breast carcinomas (excluding papillary and mucinous) for mutations in common cancer genes using polymerase chain reaction-mass spectroscopy (643 hotspot mutations across 53 genes), or semiconductor-based next-generation sequencing analysis (37 genes). Mutations were identified in 5 of 15 tumors, including 3 with PIK3CA exon 9 E542K mutations, 2 of which also harbored point mutations in FGFR family members (FGFR1 P126S, FGFR4 V550M). Single mutations were found in each of KDR (A1065T) and HRAS (G12A). PIK3CA mutations are common in other types of breast carcinoma. However, FGFR and RAS family mutations are exceedingly rare in the breast cancer literature. Likewise, activating mutations in the receptor tyrosine kinase KDR (VEGFR2) have been reported in angiosarcomas and non-small cell lung cancers; the KDR A1065T mutation is reported to be sensitive to VEGFR kinase inhibitors, and fibroblast growth factor receptor inhibitors are in trials. Our findings demonstrate the utility of broad-based genotyping in the study of rare tumors such as neuroendocrine breast cancer.

    View details for DOI 10.1097/PDM.0b013e3182a40fd1

    View details for PubMedID 25679062

  • Androgen receptor immunohistochemistry in genitourinary neoplasms INTERNATIONAL UROLOGY AND NEPHROLOGY Williams, E. M., Higgins, J. P., Sangoi, A. R., McKenney, J. K., Troxell, M. L. 2015; 47 (1): 81-85


    Androgen receptor (AR) is a recognized immunohistochemical marker of prostate cancer. However, the sensitivity and specificity of AR for prostate cancer in the setting of other genitourinary neoplasms has not been rigorously studied.We employed tissue microarrays containing prostate carcinomas, urothelial carcinomas, renal cell carcinomas, and testicular neoplasms. Slides were stained immunohistochemically for AR.Androgen receptor was positive in 95% of prostate carcinomas (n=230), but 19% of invasive urothelial carcinomas of the bladder (n=190) and 33% of non-invasive bladder urothelial carcinomas were also AR positive (N=107). Furthermore, 16% of renal pelvis urothelial carcinomas (n=43) were positive. Of primary renal cell carcinomas, 19% were AR positive (n=307). From a metastatic renal cell carcinoma cohort, 28% of metastases were AR positive (N=126). Six percent of non-teratomatous testicular germ cell tumors stained for AR (n=103).Our data show that the sensitivity of AR immunohistochemistry for prostate cancer is 94.8%. However, the specificity of AR is only 81.4%, among our cohort of invasive genitourinary tumors. Thus, we find the specificity of AR suboptimal, yet AR may remain useful as a component of an immunostain panel.

    View details for DOI 10.1007/s11255-014-0834-7

    View details for PubMedID 25218615

  • Tuberous Sclerosis-associated Renal Cell Carcinoma A Clinicopathologic Study of 57 Separate Carcinomas in 18 Patients AMERICAN JOURNAL OF SURGICAL PATHOLOGY Guo, J., Tretiakova, M. S., Troxell, M. L., Osunkoya, A. O., Fadare, O., Sangoi, A. R., Shen, S. S., Lopez-Beltran, A., Mehra, R., Heider, A., Higgins, J. P., Harik, L. R., Leroy, X., Gill, A. J., Trpkov, K., Campbell, S. C., Przybycin, C., Magi-Galluzzi, C., McKenney, J. K. 2014; 38 (11): 1457-1467


    Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with characteristic tumors involving multiple organ systems. Whereas renal angiomyolipoma (AML) is common in TSC, renal cell carcinoma (RCC) is rarely reported. Fifty-seven RCCs from 13 female and 5 male TSC patients were reviewed. Age at surgery ranged from 7 to 65 years (mean: 42 y). Nine patients (50%) had multiple synchronous and/or metachronous RCCs (range of 2 to 20 RCCs) and 5 had bilateral RCCs (28%). Seventeen patients (94%) had histologically confirmed concurrent renal AMLs, including 15 with multiple AMLs (88%) and 9 (50%) with AMLs with epithelial cysts. None of the 15 patients with available clinical follow-up information had evidence of distant metastatic disease from 6 to 198 months after their initial surgery (mean: 52 mo). The 57 RCCs exhibited 3 major distinct morphologies: (1) 17 RCCs (30%) had features similar to tumors previously described as "renal angiomyoadenomatous tumor" or "RCC with smooth muscle stroma"; (2) 34 RCCs (59%) showed features similar to chromophobe RCC; and (3) 6 RCCs (11%) showed a granular eosinophilic-macrocystic morphology. Distinct histologic changes were also commonly present in the background kidney parenchyma and included cysts or renal tubules lined by epithelial cells with prominent eosinophilic cytoplasm, nucleomegaly, and nucleoli. Immunohistochemically, all RCCs tested showed strong nuclear reactivity for PAX8 and HMB45 negativity. Compared with sporadic RCCs, TSC-associated RCCs have unique clinicopathologic features including female predominance, younger age at diagnosis, multiplicity, association with AMLs, 3 recurring histologic patterns, and an indolent clinical course. Awareness of the morphologic and clinicopathologic spectrum of RCC in this setting will allow surgical pathologists to better recognize clinically unsuspected TSC patients.

    View details for PubMedID 25093518

  • Renal pathology associated with hematopoietic stem cell transplantation. Advances in anatomic pathology Troxell, M. L., Higgins, J. P., Kambham, N. 2014; 21 (5): 330-340


    The kidney is subject to a large variety of injurious factors before, during, and after hematopoietic stem cell transplantation (HCT), leading to a high incidence of acute kidney injury in the peritransplant period. Chronic kidney disease is estimated to impact 15% to 20% of HCT recipients. Although renal biopsies may be deferred in the setting of thrombotic microangiopathy, acute self-limited impairment, or slowly progressive functional decline, in many patients renal biopsy yields important diagnostic insight to guide treatment. Light microscopic, immunofluorescence, and ultrastructural analysis often reveals a number of concurrent abnormalities in glomeruli, tubules, interstitium, and vessels. Meta-analysis of the literature reveals that membranous nephropathy is the most commonly reported glomerular lesion in the setting of HCT, followed by minimal change disease. Autopsy and biopsy studies show that clinical criteria lack sensitivity and specificity for renal acute and chronic thrombotic microangiopathy. Viral infection and other causes of interstitial nephritis and tubular injury are important findings in HCT renal biopsies, which in many instances may not be clinically suspected. Given the complexity and variability of HCT protocols, clinicopathologic correlation is needed.

    View details for DOI 10.1097/PAP.0000000000000034

    View details for PubMedID 25105935

  • Hematopoietic stem cell transplantation: graft versus host disease and pathology of gastrointestinal tract, liver, and lung. Advances in anatomic pathology Kambham, N., Higgins, J. P., Sundram, U., Troxell, M. L. 2014; 21 (5): 301-320


    Hematopoietic stem cell transplantation (HCT), formerly known as bone marrow transplantation, is an integral part of treatment for many hematological malignancies. HCT is associated with several complications and comorbidities with differential effects on a wide spectrum of organs and tissues. We present an update on HCT-associated complications such as graft versus host disease (GVHD) and infection, with focus on the surgical pathology of the gastrointestinal (GI) tract, liver, and lung. Although the grading system for GI tract acute GVHD was proposed 40 years ago, recent studies have shed light on minimal histologic criteria for diagnosis of GVHD, as well as its differential diagnosis, including histologic effects of various medications. GI dysfunction in autologous transplant recipients is increasingly appreciated and patients are often biopsied. Acute liver injury in HCT is often due to sinusoidal obstruction syndrome (previously known as venoocclusive disease), or acute GVHD. Liver dysfunction at later time posttransplantation may be associated with acute or chronic GVHD, iron overload, or other causes of hepatitis. Lung injury in HCT is multifactorial, and it remains crucially important to diagnose and treat pulmonary infections. The pulmonary biopsy yields clinically unsuspected diagnoses in the majority of cases and its utilization is likely to increase. The pathology of the skin and kidney in HCT patients are detailed in accompanying articles.

    View details for DOI 10.1097/PAP.0000000000000032

    View details for PubMedID 25105933

  • Utility of Immunohistochemical Markers in Irradiated Breast Tissue An Analysis of the Role of Myoepithelial Markers, p53, and Ki-67 AMERICAN JOURNAL OF SURGICAL PATHOLOGY Anderson, K., Williams, E. M., Kaplan, J., Matsumura, L., Troxell, M. L. 2014; 38 (8): 1128-1137


    Radiation therapy is an important adjunct to breast-conserving surgery, but the diagnosis of recurrent/de novo carcinoma in a background of radiation atypia can be difficult, especially on small biopsies. Immunostaining for myoepithelial cell proteins is often used to assess invasion in nonirradiated breast tissue, yet these stains have not been investigated specifically in irradiated breast. We studied 29 irradiated breast resection specimens, some with carcinoma in situ (CIS, n=13) and/or invasive carcinoma (n=13). Representative blocks were stained for the myoepithelial proteins p63, smooth muscle myosin heavy chain (SMM), calponin, CK5/6, the proliferative marker Ki-67, and the tumor-suppressor p53. Nonirradiated control tissue was also stained with Ki-67 and p53 (CIS, normal, contralateral). Areas of radiation atypia/atrophy and nearly all CIS in irradiated breast tissue had abundant myoepithelial cells as evidenced by SMM, calponin, and p63 stains, with focal staining attenuation or gaps with SMM and calponin and frequently absent CK5/6 staining. As predicted, myoepithelial cell staining was absent in invasive carcinoma. p63 staining revealed postradiation myoepithelial nuclear morphologic changes. p53 staining was increased, although weak, in irradiated non-neoplastic breast (12% irradiated; 4% nonirradiated); however, irradiated CIS had less p53 staining when compared with control CIS (3% irradiated; 38% nonirradiated). As expected, Ki-67 was increased in carcinoma as compared with non-neoplastic irradiated tissue. Thus, myoepithelial immunostaining is a useful diagnostic adjunct in irradiated breast, with caveats similar to nonirradiated breast. Ki-67 may be helpful in some postradiation specimens; however, p53 staining is not reliable in this setting.

    View details for PubMedID 25029119

  • Frequent phosphatidylinositol-3-kinase mutations in proliferative breast lesions MODERN PATHOLOGY Ang, D. C., Warrick, A. L., Shilling, A., Beadling, C., Corless, C. L., Troxell, M. L. 2014; 27 (5): 740-750


    The phosphatidylinositol-3-kinase pathway is one of the most commonly altered molecular pathways in invasive breast carcinoma, with phosphatidylinositol-3-kinase catalytic subunit (PIK3CA) mutations in 25% of invasive carcinomas. Ductal carcinoma in situ (DCIS), benign papillomas, and small numbers of columnar cell lesions harbor an analogous spectrum of PIK3CA and AKT1 mutations, yet there is little data on usual ductal hyperplasia and atypical ductal and lobular neoplasias. We screened 192 formalin-fixed paraffin-embedded breast lesions from 75 patients for point mutations using a multiplexed panel encompassing 643 point mutations across 53 genes, including 58 PIK3CA substitutions. PIK3CA point mutations were identified in 31/62 (50%) proliferative lesions (usual ductal hyperplasia and columnar cell change), 10/14 (71%) atypical hyperplasias (atypical ductal hyperplasia and flat epithelial atypia), 7/16 (44%) lobular neoplasias (atypical lobular hyperplasia and lobular carcinoma in situ), 10/21 (48%) DCIS, and 13/37 (35%) invasive carcinomas. In genotyping multiple lesions of different stage from the same patient/specimen, we found considerable heterogeneity; most notably, in 12 specimens the proliferative lesion was PIK3CA mutant but the concurrent carcinoma was wild type. In 11 additional specimens, proliferative epithelium and cancer contained different point mutations. The frequently discordant genotypes of usual ductal hyperplasia/columnar cell change and concurrent carcinoma support a role for PIK3CA-activating point mutations in breast epithelial proliferation, perhaps more so than transformation. Further, these data suggest that proliferative breast lesions are heterogeneous and may represent non-obligate precursors of invasive carcinoma.

    View details for DOI 10.1038/modpathol.2013.197

    View details for PubMedID 24186142

  • Membranous glomerulonephritis with crescents INTERNATIONAL UROLOGY AND NEPHROLOGY Barrett, C. M., Troxell, M. L., Larsen, C. P., Houghton, D. C. 2014; 46 (5): 963-971


    The coexistence of membranous glomerulonephritis (MGN) and necrotizing and crescentic glomerulonephritis (NCGN) is an unusual finding in a renal biopsy except in lupus nephritis. Little is known about whether these lesions are causally related in any clinical setting.We reviewed the pathology, presentation, and clinical course of 13 non-lupus patients with combined MGN and NCGN in native kidney biopsies (nine females, four males; median age 69 years), with particular attention to evidence of secondary MGN. Additional IgG subclass and phospholipase A2 receptor (PLA2R) immunofluorescence studies were conducted in seven cases.Eight biopsies were pauci-immune other than the capillary wall deposits of MGN; one patient had a non-lupus immune complex disease, and four had mesangial deposits, including one with rare subendothelial deposits. None had anti-glomerular basement membrane disease. IgG4 was dominant or codominant in the capillary wall deposits in three cases and virtually absent in four; PLA2R was positive in two cases, and negative in five. Seven patients were judged to have secondary MGN, including five of eight ANCA+ patients. Twelve patients were treated with combinations of steroids, cyclophosphamide, rituximab, followed by durable response in seven and relentless progression to end stage renal disease in four.Secondary MGN occurs with higher frequency in ANCA-positive NCGN than in the general MGN population. A causal relationship between MGN and NCGN was not established in any patient, but circumstances suggest a common cause in several, including immune complex disease, drug reaction and paraneoplastic syndrome.

    View details for DOI 10.1007/s11255-013-0593-x

    View details for PubMedID 24217802

  • Frequent PIK3CA Mutations in Radial Scars DIAGNOSTIC MOLECULAR PATHOLOGY Wolters, K. L., Ang, D., Warrick, A., Beadling, C., Corless, C. L., Troxell, M. L. 2013; 22 (4): 210-214


    Radial scars are breast lesions of uncertain pathogenesis that are associated with a 2-fold increased risk of breast cancer compared with that in controls. Activating point mutations in PIK3CA are found in 25% to 30% of invasive breast cancers; however, they have not previously been investigated in radial scars. We sought to evaluate radial scars for known activating point mutations commonly seen in invasive breast cancer. Sixteen surgical cases containing 22 radial scars were identified from pathology archives. Lesional tissue was macrodissected from unstained paraffin sections; genomic DNA was then extracted and screened for a panel of known hotspot mutations using polymerase chain reaction and mass spectroscopy analysis. Of the 22 radial scars, 14 (63.6%) had PIK3CA mutations (10 with H1047R mutations, 2 G1049R mutations, 1 E542K, 1 E545K). The remaining 8 lesions were wild type for all of the screened genes. Of the radial scars without epithelial atypia, 9/16 (56.3%) had PIK3CA mutations; furthermore, 5/6 (83.3%) radial scars with atypia had mutations detected. In this study, the frequency of PIK3CA mutations was notably higher than the 25% to 30% mutation frequency of invasive breast cancer. This finding raises interesting questions as to the role of PIK3CA mutations in breast cancer development. Additional larger studies are indicated to confirm and extend these observations in understanding the pathogenesis of radial scars and their relationship to breast cancer.

    View details for DOI 10.1097/PDM.0b013e318288b346

    View details for PubMedID 24193002

  • Light Chain Renal Amyloidosis With Prominent Giant Cells AMERICAN JOURNAL OF KIDNEY DISEASES Troxell, M. L., Griffiths, R., Schnadig, I., Houghton, D. C. 2013; 62 (6): 1193-1197


    Clinical diagnosis of amyloidosis may be very challenging because signs, symptoms, and laboratory study results can be highly variable and may overlap with other disease entities. Amyloid has characteristic features on kidney biopsy, involving glomeruli, vessels, and/or interstitium as typically amorphous waxy material that is periodic acid-Schiff pale and Congo Red birefringent under polarized light. Electron microscopy demonstrates characteristic randomly oriented fibrils. However, in rare cases, amyloid may present with atypical morphologic features on kidney biopsy, closely mimicking other histopathologic diagnoses. We present a case of light chain (AL) κ amyloidosis with an unusual inflammatory infiltrate including prominent multinucleated giant cells in the interstitium and at the glomerular hilus. Amyloid was apparent within giant cells on Congo Red staining, as well as on ultrastructural evaluation. Together with prior studies of tumoral nonrenal amyloid and renal amyloid A, we suggest that the amyloid fibril constituents κ and serum amyloid A have some predilection for inciting the rare multinucleated giant cell reaction.

    View details for DOI 10.1053/j.ajkd.2013.05.023

    View details for PubMedID 23891357

  • Evolution of immunoglobulin deposition in C3-dominant membranoproliferative glomerulopathy PEDIATRIC NEPHROLOGY Kerns, E., Rozansky, D., Troxell, M. L. 2013; 28 (11): 2227-2231


    Complement 3 glomerulopathy (C3GN) is a newly proposed subcategory of glomerular disease with features including membranoproliferative glomerulonephritis (MPGN), C3-dominant immunofluorescent staining without appreciable immunoglobulin deposition, and electron-dense deposits. Aberrations of alternative complement pathway (AP) have been found in many C3GN patients.A 13-year-old boy presented with edema in association with an upper respiratory infection. Studies demonstrated nephrotic syndrome with hematuria and markedly low C3 and C4. Initial renal biopsy showed MPGN with strong C3 and immunoglobulin deposition. The patient partially responded to immunosuppression. Follow-up biopsies at 10 months and 3 years demonstrated MPGN with strong C3, with little to no immunoglobulin deposition. Based on this and elevated SC5b-9, treatment was changed to eculizumab with further decrease in proteinuria.Serial biopsies illustrated marked variability in immunoglobulin deposition in MPGN with persistently strong C3 deposition. Whether this evolution was related to the course of disease or to therapeutic intervention, the pathologic progression documented in this series of biopsies challenges the newly proposed subcategories of MPGN.

    View details for DOI 10.1007/s00467-013-2565-x

    View details for PubMedID 23892798

  • PIK3CA-AKT pathway mutations in micropapillary breast carcinoma HUMAN PATHOLOGY Flatley, E., Ang, D., Warrick, A., Beadling, C., Corless, C. L., Troxell, M. L. 2013; 44 (7): 1320-1327


    Micropapillary carcinoma of the breast is associated with increased rates of lymph node metastasis and lymphovascular invasion. While activating point mutations in PIK3CA (encoding phosphatidylinositol-3-kinase catalytic subunit) or AKT1 are found in 25% to 30% of invasive ductal carcinomas, the mutational profile of invasive micropapillary carcinomas has not been characterized in detail. Micropapillary carcinomas, concurrent metastatic and precursor breast lesions from 19 patients were identified. Lesional tissue was punched from paraffin-tissue blocks, and genomic DNA was extracted and screened for a large panel of known hotspot mutations using multiplex polymerase chain reaction and mass-spectroscopy analysis (643 mutations in 53 genes). Hotspot point mutations were identified in 35% (7/20) of micropapillary breast carcinomas, including PIK3CA exons 7, 9 and 20 hotspots, as well as the AKT1 plekstrin homology domain mutation (E17K); mutations in TP53 and KRAS were each found in a single patient. In 6 patients, micropapillary and non-micropapillary components of the same tumor were separately tested, yielding concordant results in five; one had a wild type micropapillary component, but a PIK3CA mutation in the invasive ductal component. Concurrent lymph node metastases were mostly wild type (2/8 mutant). Accompanying ductal carcinoma in situ had point mutations in 45% (5/11), mostly concordant with invasive carcinoma; however, mutational status of other breast proliferative lesions was generally discordant with accompanying carcinoma. The rate of PIK3CA mutations in this series of micropapillary carcinomas is similar to invasive ductal carcinomas; however, there may be an enrichment of AKT1 mutations (10%). The non-micropapillary components and precursor lesions occasionally had different mutations.

    View details for DOI 10.1016/j.humpath.2012.10.018

    View details for PubMedID 23352210

  • Novel Method for PIK3CA Mutation Analysis Locked Nucleic Acid-PCR Sequencing JOURNAL OF MOLECULAR DIAGNOSTICS Ang, D., O'Gara, R., Schilling, A., Beadling, C., Warrick, A., Troxell, M. L., Corless, C. L. 2013; 15 (3): 312-318


    Somatic mutations in PIK3CA are commonly seen in invasive breast cancer and several other carcinomas, occurring in three hotspots: codons 542 and 545 of exon 9 and in codon 1047 of exon 20. We designed a locked nucleic acid (LNA)-PCR sequencing assay to detect low levels of mutant PIK3CA DNA with attention to avoiding amplification of a pseudogene on chromosome 22 that has >95% homology to exon 9 of PIK3CA. We tested 60 FFPE breast DNA samples with known PIK3CA mutation status (48 cases had one or more PIK3CA mutations, and 12 were wild type) as identified by PCR-mass spectrometry. PIK3CA exons 9 and 20 were amplified in the presence or absence of LNA-oligonucleotides designed to bind to the wild-type sequences for codons 542, 545, and 1047, and partially suppress their amplification. LNA-PCR sequencing confirmed all 51 PIK3CA mutations; however, the mutation detection rate by standard Sanger sequencing was only 69% (35 of 51). Of the 12 PIK3CA wild-type cases, LNA-PCR sequencing detected three additional H1047R mutations in "normal" breast tissue and one E545K in usual ductal hyperplasia. Histopathological review of these three normal breast specimens showed columnar cell change in two (both with known H1047R mutations) and apocrine metaplasia in one. The novel LNA-PCR shows higher sensitivity than standard Sanger sequencing and did not amplify the known pseudogene.

    View details for DOI 10.1016/j.jmoldx.2012.12.005

    View details for PubMedID 23541593

  • Enteric Oxalate Nephropathy in the Renal Allograft: An Underrecognized Complication of Bariatric Surgery AMERICAN JOURNAL OF TRANSPLANTATION Troxell, M. L., HOUGHTON, D. C., Hawkey, M., Batiuk, T. D., Bennett, W. M. 2013; 13 (2): 501-509


    Enteric hyperoxalosis is a recognized complication of bariatric surgery, with consequent oxalate nephropathy leading to chronic kidney disease and occasionally end-stage renal failure. In patients with prior gastrointestinal bypass surgery, renal allografts are also at risk of oxalate nephropathy. Further, transplant recipients may be exposed to additional causes of hyperoxalosis. We report two cases of renal allograft oxalate nephropathy in patients with remote histories of bariatric surgery. Conservative management led to improvement of graft function in one patient, while the other patient returned to dialysis. Interpretation of serologic, urine and biopsy studies is complicated by oxalate accumulation in chronic renal failure, and heightened excretion in the early posttransplant period. A high index of suspicion and careful clinicopathologic correlation on the part of transplant nephrologists and renal pathologists are required to recognize and treat allograft oxalate nephropathy. As the incidence of obesity and pretransplant bariatric surgery increases in the transplant population, allograft oxalate nephropathy is likely to be an increasing cause of allograft dysfunction.

    View details for DOI 10.1111/ajt.12029

    View details for PubMedID 23311979

  • Mucinous breast carcinomas lack PIK3CA and AKT1 mutations HUMAN PATHOLOGY Kehr, E. L., Jorns, J. M., Ang, D., Warrick, A., Neff, T., Degnin, M., Lewis, R., Beadling, C., Corless, C. L., Troxell, M. L. 2012; 43 (12): 2207-2212


    Activating point mutations in the phosphatidylinositol-3-kinase catalytic subunit (PIK3CA) are among the most common molecular defects in invasive breast cancer. Point mutations in the downstream kinase AKT1 are seen in a minority of carcinomas. These mutations are found preferentially in estrogen receptor-positive and Her2-positive breast carcinomas; however, special morphologic types of breast cancer have not been well studied. Twenty-nine cases of pure invasive mucinous carcinoma and 9 cases of ductal carcinoma with mucinous differentiation were screened for a panel of point mutations (>321 mutations in 30 genes) using a multiplex polymerase chain reaction panel with mass spectroscopy readout. In addition, associated ductal carcinoma in situ, hyperplasia, or columnar cell lesions were separately tested where available (25 lesions). In 3 invasive cases and 15 ductal carcinoma in situ/proliferative lesions, PIK3CA hotspot mutations were, instead, tested by direct sequencing. No point mutations were identified in invasive mucinous breast carcinoma. This contrasts with the 35% frequency of PIK3CA mutations in a comparative group of invasive ductal carcinomas of no special type. Interestingly, PIK3CA hotspot point mutations were identified in associated ductal carcinoma in situ (3/14) and hyperplasia (atypical ductal hyperplasia [2/3], usual ductal hyperplasia [2/3], columnar cell change [1/5]), suggesting that PIK3CA mutations may play a role in breast epithelial proliferation. This series represents the largest study, to date, of PIK3CA genotyping in mucinous carcinoma and supports the unique pathogenetics of invasive mucinous breast carcinoma.

    View details for DOI 10.1016/j.humpath.2012.03.012

    View details for PubMedID 22705004

  • Phosphatidylinositol-3-kinase pathway mutations are common in breast columnar cell lesions MODERN PATHOLOGY Troxell, M. L., Brunner, A. L., Neff, T., Warrick, A., Beadling, C., Montgomery, K., Zhu, S., Corless, C. L., West, R. B. 2012; 25 (7): 930-937


    The phosphatidylinositol-3-kinase pathway is one of the most commonly mutated pathways in invasive breast carcinoma, with PIK3CA mutations in ∼25% of invasive carcinomas, and AKT1 mutations in up to 5%. Ductal carcinoma in situ, and benign papillomas harbor similar mutations. However, activating point mutations in breast columnar cell lesions have been infrequently studied. Twenty-three breast resection specimens containing columnar cell lesions were identified; 14 with associated invasive carcinoma or carcinoma in situ. DNA extracts were prepared from formalin-fixed paraffin-embedded tissue and screened for a panel of point mutations (321 mutations in 30 genes) using a multiplex PCR panel with mass-spectroscopy readout. PIK3CA mutations were identified in 13/24 columnar cell lesions (54%) and 3/8 invasive carcinomas (37%). The mutation status of columnar cell lesions and associated carcinoma was frequently discordant. Of the 14 cases, only 5 demonstrated the same genotype in matched samples of columnar cell lesions and carcinoma (4 wild type, 1 PIK3CA H1047R). Interestingly, five patients had mutations in columnar cell lesions with wild-type carcinoma; two patients had different point mutations in columnar cell lesions and carcinoma. Only three cases had wild-type columnar cell lesion and mutated carcinoma. The 50% PIK3CA mutation prevalence in columnar cell lesions is greater than reported in most studies of invasive breast cancer. Further, columnar cell lesions and carcinoma were frequently discordant for PIK3CA/AKT1 mutation status. These findings raise interesting questions about the role of PIK3CA/AKT pathway in breast carcinogenesis, and the biologic/precursor potential of columnar cell lesions.

    View details for DOI 10.1038/modpathol.2012.55

    View details for PubMedID 22460814

  • Patterns of IgG Subclass Deposits in Membranous Glomerulonephritis in Renal Allografts TRANSPLANTATION PROCEEDINGS Kearney, N., Podolak, J., Matsumura, L., Houghton, D., Troxell, M. 2011; 43 (10): 3743-3746


    Membranous glomerulonephritis (MGN) may develop in the renal allograft either de novo or as a recurrence. These 2 forms of MGN may have different pathogenic mechanisms, with different IgG subclass profiles in the immune deposits. This study examined IgG subclass distributions in recurrent and de novo MGN in allograft kidneys.We identified allograft kidneys with MGN, including 7 with recurrent MGN, 2 with de novo MGN, and 2 atypical/indeterminate, and determined the relative intensity of IgG1, IgG2, IgG3, and IgG4 staining in capillary wall deposits by immunofluorescence microscopy.IgG4 was the dominant or codominant IgG subclass in capillary loop deposits in all 7 cases of recurrent MGN. IgG1 staining was dominant in 3 of 4 de novo or atypical MGN cases and codominant with IgG4 in the fourth.Although pretransplantation kidney biopsies were not available for comparisons, these findings suggest that all allograft recurrences represent idiopathic MGN and that de novo MGN cases had a different pathogenic mechanism.

    View details for DOI 10.1016/j.transproceed.2011.10.042

    View details for PubMedID 22172838

  • An abundance of IgG4+plasma cells is not specific for IgG4-related tubulointerstitial nephritis MODERN PATHOLOGY Houghton, D. C., Troxell, M. L. 2011; 24 (11): 1480-1487


    IgG4-related tubulointerstitial nephritis (IgG4-TIN), the renal parenchymal lesion of IgG4-related sclerosing disease, is characterized, among other things, by the presence of numerous IgG4-positive plasma cells (IgG4+PC) in the kidney infiltrate. The specificity of this finding for IgG4-TIN has not been addressed. To address this we examined 100 consecutive renal biopsy samples with active interstitial inflammation for the presence of IgG4+PC, and correlated the findings with principal diagnosis, the available clinical histories, and the findings in four biopsy samples of IgG4-TIN. Eleven of the survey biopsy samples contained an average of more than 10 IgG4+PC per × 200 field, including two with IgG4+PC in numbers comparable to those in two of the IgG4-related tubulointerstitial disease biopsy samples. The principal pathological diagnoses in the IgG4+PC-rich cases included anti-neutrophil cytoplasmic antibody-positive necrotizing glomerulonephritis (five cases), diabetic nephropathy (two cases), idiopathic interstitial nephritis (two cases), membranous glomerulonephritis (one case), and lupus nephritis (one case). There was no reason, based on histology or clinical history, to believe that any of these cases represented previously unsuspected IgG4-related tubulointerstitial disease. We conclude that the presence of numerous IgG4+PC is essential to, but not sufficient for, the diagnosis of IgG4-TIN.

    View details for DOI 10.1038/modpathol.2011.101

    View details for PubMedID 21701536

  • Guidelines for the Diagnosis of Antibody-Mediated Rejection in Pancreas Allografts-Updated Banff Grading Schema AMERICAN JOURNAL OF TRANSPLANTATION Drachenberg, C. B., Torrealba, J. R., Nankivell, B. J., Rangel, E. B., Bajema, I. M., Kim, D. U., Arend, L., Bracamonte, E. R., Bromberg, J. S., Bruijn, J. A., Cantarovich, D., Chapman, J. R., Farris, A. B., Gaber, L., Goldberg, J. C., Haririan, A., Honsova, E., Iskandar, S. S., Klassen, D. K., Kraus, E., Lower, F., Odorico, J., Olson, J. L., Mittalhenkle, A., Munivenkatappa, R., Paraskevas, S., Papadimitriou, J. C., Randhawa, P., Reinholt, F. P., Renaudin, K., Revelo, P., Ruiz, P., Samaniego, M. D., Shapiro, R., Stratta, R. J., Sutherland, D. E., Troxell, M. L., Voska, L., Seshan, S. V., Racusen, L. C., Bartlett, S. T. 2011; 11 (9): 1792-1802


    The first Banff proposal for the diagnosis of pancreas rejection (Am J Transplant 2008; 8: 237) dealt primarily with the diagnosis of acute T-cell-mediated rejection (ACMR), while only tentatively addressing issues pertaining to antibody-mediated rejection (AMR). This document presents comprehensive guidelines for the diagnosis of AMR, first proposed at the 10th Banff Conference on Allograft Pathology and refined by a broad-based multidisciplinary panel. Pancreatic AMR is best identified by a combination of serological and immunohistopathological findings consisting of (i) identification of circulating donor-specific antibodies, and histopathological data including (ii) morphological evidence of microvascular tissue injury and (iii) C4d staining in interacinar capillaries. Acute AMR is diagnosed conclusively if these three elements are present, whereas a diagnosis of suspicious for AMR is rendered if only two elements are identified. The identification of only one diagnostic element is not sufficient for the diagnosis of AMR but should prompt heightened clinical vigilance. AMR and ACMR may coexist, and should be recognized and graded independently. This proposal is based on our current knowledge of the pathogenesis of pancreas rejection and currently available tools for diagnosis. A systematized clinicopathological approach to AMR is essential for the development and assessment of much needed therapeutic interventions.

    View details for DOI 10.1111/j.1600-6143.2011.03670.x

    View details for Web of Science ID 000294360400007

    View details for PubMedID 21812920

  • PAX2 Expression in Wilms Tumors and Other Childhood Neoplasms AMERICAN JOURNAL OF SURGICAL PATHOLOGY Davis, J. L., Matsumura, L., Weeks, D. A., Troxell, M. L. 2011; 35 (8): 1186-1194


    PAX2 plays an important role in kidney development; although small studies have demonstrated PAX2 expression in Wilms tumors (WT), comprehensive studies on formalin-fixed tissue are lacking. Thus, we systematically evaluated PAX2 immunohistochemical staining in a retrospective study of pediatric WT, as compared with other pediatric tumors. We stained formalin-fixed, paraffin-embedded sections from 39 WT, 6 nephrogenic rests, 8 non-Wilms renal tumors, and 43 nonrenal pediatric small round cell tumors with 2 different PAX2 polyclonal antibodies. PAX2 demonstrated strong, diffuse staining of epithelial and blastema components of WT (97% of cases). PAX2 stained WT stroma in fewer cases (23%), but 80% of anaplastic foci were positive. Nephrogenic rests, 1 case of metanephric adenoma, and 1 pediatric renal cell carcinoma were also PAX2 positive; other pediatric renal tumors were negative. Neuroblastoma, primitive neuroectodermal tumor/Ewings, and T-cell acute lymphoblastic lymphoma (ALL) were PAX2 negative. However, PAX2 weakly stained some cases of B-cell ALL rhabdomyosarcoma (RMS) was also stained, especially alveolar RMS (83%), with less staining of embryonal RMS (13%). One of the antibodies also stained maturing myoid cytoplasm of WT and RMS. This study shows that PAX2 is a sensitive marker of WT (sensitivity 97%), but PAX2 shows weak-to-moderate-intensity nuclear staining of RMS and B-cell ALL, somewhat limiting its utility. However, PAX2 may be a helpful marker in certain diagnostic situations. We speculate that RMS and B-cell ALL staining could be due to antibody cross-reactivity with PAX family members with known expression in RMS and B-cell ALL.

    View details for DOI 10.1097/PAS.0b013e31821d3131

    View details for PubMedID 21730820

  • Acute kidney injury with cryoglobulinemic peritubular neutrophilic capillaritis CLINICAL NEPHROLOGY Troxell, M. L., Shackleton, D. V., Raguram, P., HOUGHTON, D. C. 2011; 76 (2): 159-165


    Neutrophil predominant capillaritis and interstitial inflammation is an uncommon renal biopsy finding, with a broad differential diagnosis.A 77-year-old woman presented with a complicated history including vasculitis, cryoglobulinemia, malaise, and systemic symptoms, which progressed to acute kidney injury. Renal biopsy demonstrated prominent neutrophilic capillaritis with interstitial inflammation, and fibrinoid deposits in medullary capillaries and interstitium. Glomeruli showed membranoproliferative glomerulonephritis, but no crescents or necrosis.We interpret the capillary and interstitial changes as evidence of cryoglobulin-associated vasculitis, and discuss the differential diagnosis of this uncommon histologic pattern of renal pathology, including other vasculitides, infection, ischemia-infarction, collagen vascular disease, and antibody-mediated allograft rejection, among others.

    View details for DOI 10.5414/CN106626

    View details for PubMedID 21762649

  • Immunohistochemical and Molecular Markers in Breast Phyllodes Tumors APPLIED IMMUNOHISTOCHEMISTRY & MOLECULAR MORPHOLOGY Korcheva, V. B., Levine, J., Beadling, C., Warrick, A., Countryman, G., Olson, N. R., Heinrich, M. C., Corless, C. L., Troxell, M. L. 2011; 19 (2): 119-125


    Phyllodes tumors of the breast are diagnostically and managerially enigmatic, as their malignant potential is difficult to predict based on the standard morphologic criteria. Thus, there is a need for additional markers of biologic potential. Although a number of ancillary tests have been reported, consensus in the literature is lacking. We studied 38 cellular fibroadenomas and phyllodes tumors of various grade (World Health Organization benign, borderline, and malignant) with a panel of immunohistochemical stains (p53, CD117, phospho-Histone3, mdm2, cdk4) and screened 26 of the tumors for mutations across 30 cancer-related genes using PCR and mass-spectrometry based methods. p53 and phospho-Histone3 (mitotic marker) showed increased staining in higher grade phyllodes tumors. CD117, mdm2, and cdk4 showed no difference in expression across different grades of phyllodes tumors. Mutational analysis revealed an S8R substitution in FBX4 (an E3 ubiquitin ligase) in 3 cases: 1 benign and 2 borderline. The S8R substitution seems to be more common in phyllodes tumors (11.5%) as compared with other cancers. FBX4 S8R cases had high cyclin D1 expression, but this finding was not specific. Our data support earlier studies showing that p53 has potential use in pathologic assessment of phyllodes tumors, and we newly characterized phospho-Histone3 for this application. Further studies are needed to characterize the molecular pathogenesis of the phyllodes tumors, as we were unable to identify activating mutations despite screening for a large panel of activating hotspot mutations. The significance of the FBX4 substitution deserves further investigation.

    View details for DOI 10.1097/PAI.0b013e3181f5349a

    View details for Web of Science ID 000287190000006

    View details for PubMedID 21030860

  • Glomerular fibrin thrombi in ABO and crossmatch compatible renal allograft biopsies PATHOLOGY RESEARCH AND PRACTICE Troxell, M. L., Norman, D., Mittalhenkle, A. 2011; 207 (1): 15-23


    Glomerular fibrin thrombi may be an early indication of antibody-mediated rejection in renal allograft biopsies. However, fibrin thrombi have a broad differential; thus, we sought to evaluate the etiology and implications of glomerular fibrin thrombi in allograft biopsies of blood group and cytotoxic crossmatch compatible renal allografts. Biopsies were identified from the pathology files of Oregon Health & Science University. Detailed histopathologic findings were retrospectively correlated with clinical data, treatment, and outcome. Sixteen early posttransplant biopsies had glomerular fibrin thrombi, including three surveillance biopsies. Six of 16 biopsies had no other histopathologic findings; 5/16 had glomerulitis and peritubular capillaritis; 4/16 had concomitant cellular vascular rejection; one had parenchymal infarction. C4d staining was positive in 4/16 cases. Most patients were treated with IVIg and plasmapheresis, others with rapamycin, thymoglobulin, or rituximab. At an average follow-up of 62 months, 8 patients with functioning grafts had a mean serum creatinine of 1.4 mg/dL (122 μmol/L). Antibody-mediated rejection is an important consideration in blood group compatible allograft biopsies with glomerular fibrin thrombi, even with C4d-negative biopsies. However, multidisciplinary evaluation is necessary, given other etiologies, including drug toxicity, hemolytic-uremia syndrome, and large vessel thrombosis. Despite aggressive treatment, both short and long-term graft survival may be compromised.

    View details for DOI 10.1016/j.prp.2010.10.001

    View details for PubMedID 21067871

  • Distinctive Morphology of Renal Cell Carcinomas in Tuberous Sclerosis INTERNATIONAL JOURNAL OF SURGICAL PATHOLOGY Schreiner, A., Daneshmand, S., Bayne, A., Countryman, G., Corless, C. L., Troxell, M. L. 2010; 18 (5): 409-418


    Tuberous sclerosis complex results from mutations in 1 of 2 interacting gene products, hamartin or tuberin. The syndrome is characterized by hamartomas and neoplastic lesions, including angiomyolipomas of the kidney and other organs. Renal cell carcinoma (RCC) in tuberous sclerosis remains relatively poorly characterized because historical studies were confounded by the inclusion of epithelioid angiomyolipomas. The authors present a patient with tuberous sclerosis and bilateral renal lesions, including multiple minute angiomyolipomas, cortical cysts, and 4 separate RCCs of unclassified type. The carcinomas shared distinctive morphological features, including sheet-like, glandular, trabecular, or cystic architecture and abundant granular eosinophilic cytoplasm. By definition, the carcinomas were keratin positive and negative for HMB-45 and Melan-A. Detailed immunohistochemical analysis revealed heterogeneity among the cortical cysts and carcinomas. The histopathological features of these carcinomas illustrate characteristics of renal carcinoma that are probably related to genetic alterations of tuberous sclerosis.

    View details for DOI 10.1177/1066896909333510

    View details for PubMedID 19403547

  • Pancreas Allograft Rejection: Analysis of Concurrent Renal Allograft Biopsies and Posttherapy Follow-Up Biopsies TRANSPLANTATION Troxell, M. L., Koslin, D. B., Norman, D., Rayhill, S., Mittalhenkle, A. 2010; 90 (1): 75-84


    Pancreas and kidney allograft function is routinely monitored with serum studies (amylase, lipase, and creatinine). Increased levels commonly prompt tissue biopsy, to diagnose cause of graft dysfunction. Historically, pancreas allografts were infrequently biopsied, although serum enzymes and renal rejection may be poor surrogates for pancreas status.Pancreas allograft biopsies at our center were reviewed and reclassified according to University of Maryland (UMD) and Banff criteria; C4d immunostaining was performed. Findings were correlated with clinical data and renal allograft biopsies.Fifty-six pancreas allograft biopsies from 27 patients were evaluated. UMD and Banff grading were similar, although two UMD "indeterminate" biopsies were Banff grade 1 rejection. There were 21 concurrent pancreas and renal biopsies, all from simultaneous pancreas-kidney allograft recipients. Thirteen pairs were concordant for rejection; eight pairs were discordant for rejection (38%); six pairs showed pancreas rejection without kidney rejection, and two pairs showed the converse. Fourteen patients had a total of 21 follow-up pancreas allograft biopsies. Seven biopsies showed a lower grade of rejection on follow-up biopsy, 4 biopsies showed more severe rejection, and 10 had unchanged grade. In only 9 of these 21 (43%) cases, did the interval serum amylase or lipase trend parallel the subsequent biopsy diagnosis.With a high biopsy discordance rate, our data suggest that renal allograft rejection is a poor surrogate for pancreas allograft status. Likewise, serum amylase and lipase levels do not predict response to rejection therapy. Surveillance or posttherapy pancreas allograft biopsies may be a useful means to monitor pancreas allograft status.

    View details for DOI 10.1097/TP.0b013e3181dda17e

    View details for PubMedID 20548259

  • Glomerular basement membrane lipidosis in Alagille syndrome PEDIATRIC NEPHROLOGY Davis, J., Griffiths, R., Larkin, K., Rozansky, D., Troxell, M. 2010; 25 (6): 1181-1184


    Alagille syndrome is characterized by a paucity of interlobular bile ducts with chronic cholestasis, cardiac, skeletal, and eye abnormalities and is associated predominantly with JAG1 mutations. Various renal abnormalities have been sporadically described. The classic renal histopathology described in Alagille syndrome is mesangiolipidosis, with lipid deposits predominately confined to the mesangium and minimal deposition within the glomerular basement membrane (GBM). We report a 5-year-old girl with Alagille syndrome who presented with persistent subnephrotic proteinuria and renal tubular acidosis. A renal biopsy showed GBM irregularities (mimicking membranous glomerulonephritis), mesangial sclerosis, and focal segmental glomerulosclerosis (FSGS) on light microscopy. Electron microscopy revealed few lipid inclusions within the mesangium but extensive inclusions along the GBM. These findings are mostly consistent with those reported previously in Alagille syndrome. However, the histologic distribution of lipid vacuoles is seemingly reversed in this patient and is uniquely accompanied by FSGS, emphasizing the spectrum of renal histopathology seen in Alagille syndrome. The proteinuria observed in this patient is likely attributed to significant GBM lipid deposition, which over time may contribute to the development of FSGS.

    View details for DOI 10.1007/s00467-009-1426-0

    View details for PubMedID 20091053

  • Factors influencing accuracy of axillary sentinel lymph node frozen section for breast cancer 96th Annual Meeting of the North-Pacific-Surgical-Association Jensen, A. J., Naik, A. M., Pommier, R. F., Vetto, J. T., Troxell, M. L. EXCERPTA MEDICA INC-ELSEVIER SCIENCE INC. 2010: 629–34


    Intraoperative sentinel lymph node (SLN) frozen section (FS) guides immediate axillary lymph node dissection in breast cancer patients.The Oregon Health & Science University pathology database was searched for SLN FS From October 1999 to January 1, 2009. Slides of positive cases were reviewed and metastasis sizes measured.Of 416 cases, 129 were positive (31%) on permanent sections and immunohistochemistry, with 79 concordant and 50 false-negative FS. Accuracy was 88%, sensitivity 61%, and specificity 100%. FS accuracy for lobular carcinoma (76%) was lower than for invasive ductal carcinoma (88%) (P = .048). FS accuracy significantly differed by size of nodal tumor. For 49 cases of tumor 2-mm metastases, accuracy was 90% (P < .0001).False-negative FS were predominantly small nodal tumor deposits not sampled at FS. Although accuracy was lower, SLN FS is still beneficial in lobular carcinoma, but not ductal carcinoma in situ.

    View details for DOI 10.1016/j.amjsurg.2010.01.017

    View details for PubMedID 20466107

  • Phosphatidylinositol-3-kinase and AKT1 mutations occur early in breast carcinoma BREAST CANCER RESEARCH AND TREATMENT Dunlap, J., Le, C., Shukla, A., Patterson, J., Presnell, A., Heinrich, M. C., Corless, C. L., Troxell, M. L. 2010; 120 (2): 409-418


    Mutationally activated protein kinases are appealing therapeutic targets in breast carcinoma. Mutations in phosphatidylinositol-3-kinase (PI3KCA) have been described in 8-40% of invasive breast carcinomas, and AKT1 mutations have been characterized in 1-8% of breast carcinomas. However, there is little data on these mutations in breast precursor lesions. To further delineate the molecular evolution of breast tumorigenesis, samples of invasive breast carcinoma with an accompanying in situ component were macro dissected from formalin-fixed paraffin embedded tissue and screened for mutations in PIK3CA exons 7, 9, 20, and AKT1 exon 2. Laser capture micro dissection (LCM) was performed on mutation-positive carcinomas to directly compare the genotypes of separated invasive and in situ tumor cells. Among 81 cases of invasive carcinoma, there were eight mutations in PIK3CA exon 20 (7 H1047R, 1 H1047L) and four mutations in exon 9 (2 E545K, 1 E542K, 1 E545G), totaling 12/81 (14.8%). In 11 cases examined, paired LCM in situ tumor showed the identical PIK3CA mutation in invasive and in situ carcinoma. Likewise, 3 of 78 (3.8%) invasive carcinomas showed an AKT1 E17K mutation, and this mutation was identified in matching in situ carcinoma in both informative cases. Mutational status did not correlate with clinical parameters including hormone receptor status, grade, and lymph node status. The complete concordance of PIK3CA and AKT1 mutations in matched samples of invasive and in situ tumor indicates that these mutations occur early in breast cancer development and has implications with regard to therapeutics targeted to the PI3 kinase pathway.

    View details for DOI 10.1007/s10549-009-0406-1

    View details for PubMedID 19418217

  • High prevalence of PIK3CA/AKT pathway mutations in papillary neoplasms of the breast MODERN PATHOLOGY Troxell, M. L., Levine, J., Beadling, C., Warrick, A., Dunlap, J., Presnell, A., Patterson, J., Shukla, A., Olson, N. R., Heinrich, M. C., Corless, C. L. 2010; 23 (1): 27-37


    Papillary lesions of the breast have an uncertain relationship to the histogenesis of breast carcinoma, and are thus diagnostically and managerially challenging. Molecular genetic studies have provided evidence that ductal carcinoma in situ and even atypical ductal hyperplasia are precursors of invasive carcinoma. However, papillary lesions have been seldom studied. We screened papillary breast neoplasms for activating point mutations in PIK3CA, AKT1, and RAS protein-family members, which are common in invasive ductal carcinomas. DNA extracts were prepared from sections of 89 papillary lesions, including 61 benign papillomas (28 without significant hyperplasia; 33 with moderate to florid hyperplasia), 11 papillomas with atypical ductal hyperplasia, 7 papillomas with carcinoma in situ, and 10 papillary carcinomas. Extracts were screened for PIK3CA and AKT1 mutations using mass spectrometry; cases that were negative were further screened for mutations in AKT2, BRAF, CDK, EGFR, ERBB2, KRAS, NRAS, and HRAS. Mutations were confirmed by sequencing or HPLC assay. A total of 55 of 89 papillary neoplasms harbored mutations (62%), predominantly in AKT1 (E17K, 27 cases) and PIK3CA (exon 20 >exon 9, 27 cases). Papillomas had more mutations in AKT1 (54%) than in PIK3CA (21%), whereas papillomas with hyperplasia had more PIK3CA (42%) than AKT1 (15%) mutations, as did papillomas with atypical ductal hyperplasia (PIK3CA 45%, AKT1 27%, and NRAS 9%). Among seven papillomas with carcinoma in situ, three had AKT1 mutations. The 10 papillary carcinomas showed an overall lower frequency of mutations, including 1 with an AKT1 mutation (in a tumor arising from a papilloma), 1 with an NRAS gene mutation (Q61H), and 2 with PIK3CA mutations (1 overlapping with the NRAS Q61H). These findings indicate that approximately two-thirds of papillomas are driven by mutations in the PI3CA/AKT pathway. Some papillary carcinomas may arise from these lesions, but others may have different molecular origins.

    View details for DOI 10.1038/modpathol.2009.142

    View details for PubMedID 19898424

  • Rejection Versus Posttransplantation Lymphoproliferative Disorder in a Renal Transplant Recipient AMERICAN JOURNAL OF KIDNEY DISEASES Troxell, M. L., Dunlap, J. B., Mittalhenkle, A., Ishag, M., Fan, G., Huang, J. Z., Gatter, K., Byrd, D. M., Webster, D., Houghton, D. C. 2008; 52 (6): 1174-1179

    View details for DOI 10.1053/j.ajkd.2008.04.033

    View details for PubMedID 18706749

  • Renal pathology in hematopoietic cell transplantation recipients 96th Annual Meeting of the United-States-and-Canadian-Academy-of-Pathology Troxell, M. L., Pilapil, M., Miklos, D. B., Higgins, J. P., Kambham, N. NATURE PUBLISHING GROUP. 2008: 396–406


    Hematopoietic cell transplantation-associated renal injury may be related to a combination of factors including chemotherapy, radiation, infection, immunosuppressive agents, ischemia, and graft-versus-host disease. Renal biopsy specimens from hematopoietic cell transplant recipients at two institutions (Stanford University Medical Center and Oregon Health & Science University) were reviewed in correlation with clinical data. Fifteen cases were identified (post hematopoietic cell transplant time 0.7-14.5 years), including six with autologous hematopoietic cell transplant. Indications for renal biopsy included proteinuria (n=13; nephrotic range in 8), increased serum creatinine (n=10), or both (n=6). Many patients had multiple pathologic findings on renal biopsy. Membranous glomerulonephritis was the most common diagnosis (n=7), including two patients with autologous hematopoietic cell transplant and five with evidence of chronic graft-versus-host disease elsewhere. Four membranous glomerulonephritis patients achieved sustained remission with rituximab therapy. Other glomerular pathology included focal segmental glomerulosclerosis (n=1) and minimal change disease (n=1). Evidence of thrombotic microangiopathy was common (in isolation or combined with other pathology), as was acute tubular necrosis and tubulointerstitial nephritis. Of 14 patients with follow-up (2-64 months, mean 19 months), 6 had chronic renal insufficiency (serum creatinine >1.5 mg/dl), 2 had end stage renal disease, and 6 had essentially normal renal function. Our retrospective study shows that renal dysfunction in hematopoietic cell transplant recipients is often multifactorial, and biopsy may reveal treatable causes. Membranous glomerulonephritis is seen in autologous and allogeneic hematopoietic cell transplant recipients, and may respond to anti-B-cell therapy, which has implications regarding pathogenesis and relationship to graft-versus-host disease.

    View details for DOI 10.1038/modpathol.3801011

    View details for PubMedID 18223556

  • Immunohistochemical staining of papillary breast lesions APPLIED IMMUNOHISTOCHEMISTRY & MOLECULAR MORPHOLOGY Troxell, M. L., Masek, M., Sibley, R. K. 2007; 15 (2): 145-153


    The separation of ductal papilloma from intraductal papillary carcinoma of the breast on hematoxylin and eosin stained sections often presents diagnostic difficulty. Immunohistochemical staining is often employed in diagnosis, historically with smooth muscle actin (SMA). In this study, the staining characteristics of a panel of myoepithelial markers (calponin, p63, P-cadherin), were compared with SMA, and the epithelial expression of CD44s was assessed in 99 papillary lesions. SMA, calponin, and p63 demonstrated myoepithelial cells in 61%, 63%, and 65% of papillary lesions, respectively. However, specificity was quite variable. Calponin-stained stromal myofibroblasts (35% of cases), vessel pericytes (92%), and endothelial cells (69%), though each to a lesser degree than SMA. Calponin also showed cross reactivity with epithelium in 18% of cases. p63 was almost completely restricted to myoepithelial cell nuclei, and did not stain vascular smooth muscle or myofibroblasts. However, p63 stained the epithelial component in one papillary carcinoma, a basal layer of cells in 1 biphasic invasive carcinoma, and the cytoplasm in 1 case. P-cadherin stained both epithelial and myoepithelial cells. The epithelial expression of CD44s and did not distinguish papillomas from papillary carcinomas. Thus, P-cadherin and CD44s are not useful in the characterization of papillary lesions. Given increased specificity as compared with SMA, the combination of p63 and calponin is recommended for analysis of breast papillary lesions.

    View details for Web of Science ID 000246870200005

    View details for PubMedID 17525625

  • Evaluation of Her-2/neu status in carcinomas with amplified chromosome 17 centromere locus AMERICAN JOURNAL OF CLINICAL PATHOLOGY Troxell, M. L., Bangs, C. D., Lawce, H. J., Galperin, I. B., Baiyee, D., West, R. B., Olson, S. B., Cherry, A. M. 2006; 126 (5): 709-716


    Accurate assessment of Her-2/neu (erb-b2) status in breast carcinoma is essential for therapy planning. Clinical assays are targeted at protein overexpression (immunohistochemical analysis) or gene amplification (fluorescence in situ hybridization [FISH]). Cases with aberrant FISH signal patterns are problematic and may lead to underreporting of Her-2/neu amplification. We performed FISH with additional chromosome 17 probes, SMS (Smith-Magenis syndrome critical region) and RARA (retinoic acid receptor), on 7 cases with unusual Her-2/CEP17 (chromosome 17 centromere control probe) results to assess whether different measurements of chromosome 17 copy number might clarify the Her-2/neu amplicon status. Although the Her-2/CEP17 ratio scores were within normal range (<2.0), the Her-2/SMS or Her-2/RARA ratio revealed amplification of Her-2/neu in 5 of 7 cases. Immunohistochemical analysis demonstrated Her-2/neu protein overexpression in the same 5 cases only. We describe novel application of SMS/RARA FISH probes for assessing cases with complex Her-2/CEP17 FISH patterns. Such additional data, correlated with immunohistochemical analysis, may help guide therapy in patients with breast carcinoma.

    View details for DOI 10.1309/9EYM6VE58F2YCD9F

    View details for PubMedID 17050068

  • Evaluation of C4d staining in liver and small intestine allografts 93rd Annual Meeting of the United-States-and-Canadian-Academy-of-Pathology Troxell, M. L., Higgins, J. P., Kambham, N. COLLEGE AMER PATHOLOGISTS. 2006: 1489–96


    Antibody-mediated humoral rejection in kidney and heart allografts is well recognized and is often associated with poor outcome. C4d deposition in allograft biopsy specimens occurs at sites of antibody-mediated complement activation and has become one of the histopathologic criteria for diagnosis of humoral rejection in the kidney and the heart.To study immunohistochemical C4d staining as a potential diagnostic marker in liver and small intestine allograft biopsy specimens.Thirty-six small intestine and 71 liver specimens, including native specimens, allografts with and without histologic features of acute cellular rejection, and explants, were stained with antisera to C4d using an immunohistochemical method on formalin-fixed, paraffin-embedded tissue.In small intestine, C4d labeled capillaries in 27% of cases with no evidence of rejection, 36% of cases with evidence of acute rejection, and 2 (28%) of 7 specimens of native normal small intestine. In liver allograft biopsy specimens, C4d stained endothelium of veins, arteries, and/or sinusoids in 2 (8%) of 25 cases of acute rejection with central vein involvement; C4d staining was negative in biopsy specimens with no evidence of rejection. C4d stained the endothelium in a subset of explanted liver allografts with ductopenic rejection or chronic vascular rejection and strongly stained 1 explant with features of hyperacute rejection.The clinical utility of C4d staining in solid organ transplantation may vary by organ. Our data show C4d is unlikely to have utility in small intestine allograft biopsy specimens; however, further study in liver allografts, in conjunction with donor-specific antibody testing, is warranted.

    View details for Web of Science ID 000241049200013

    View details for PubMedID 17090190

  • Comparison of C4d immunostaining methods in renal allograft biopsies 8th Banff Conference on Allograft Pathology Troxell, M. L., Weintraub, L. A., Higgins, J. P., Kambham, N. AMER SOC NEPHROLOGY. 2006: 583–91


    Immunostaining of renal allograft biopsies for C4d deposition has become an important diagnostic tool in the recognition of humoral-mediated graft rejection. The majority of studies have been performed on frozen tissue sections with one of several commercially available antibody reagents. However, only a single small series that compared reagents or methods, including staining of formalin-fixed, paraffin-embedded tissue, has been published. Two different staining methods in 138 renal allograft biopsies were compared directly: A mAb (Quidel, San Diego, CA) on frozen tissue sections with indirect immunofluorescence (IF) and a polyclonal antibody (Biomedica Gruppe, distributed by ALPCO, Windham, NH) applied to formalin-fixed, paraffin-embedded tissue with immunohistochemical (IHC) detection. An initial data set of 107 consecutive cases showed complete agreement between staining methods in 104 (97%) cases. Overall, nine of 107 cases were positive with one or both methods, representing 8.4% of all allograft biopsies tested, 15% of clinically indicated biopsies, and 24% of biopsies with a histologic diagnosis of acute cellular rejection. A second set of 31 cases included 17 cases that were positive by either method, with concordance in 29 of 31 cases. Combining the two data sets, the overall specificity of the IHC method compared with IF was 98%, and sensitivity was 87.5%. Direct comparison demonstrates that IHC staining of formalin-fixed, paraffin-embedded tissue with anti-C4d polyclonal antibody has acceptable sensitivity and specificity, as compared with IF staining of frozen tissue with the Quidel mAb.

    View details for PubMedID 17699262

  • Glomerular and tubular basement membrane calcinosis: Case report and literature review AMERICAN JOURNAL OF KIDNEY DISEASES Troxell, M. L., Higgins, J. P., Sibley, R. K. 2006; 47 (2)


    Nephrocalcinosis most commonly manifests as renal calculi or deposition within the tubulointerstitial compartment. Conversely, calcium deposition within glomeruli is extremely rare. We present the case of a 50-year-old man with multiple medical problems, including hepatitis C, diabetes, hypertension, proteinuria, and chronic renal failure. Renal biopsy showed impressive calcium deposits along glomerular basement membranes and tubular basement membranes, within intracellular organelles, and in the interstitium in the setting of a normal serum calcium level. Seven months after biopsy, the patient is on hemodialysis therapy. Although serological and medical examination failed to show a treatable cause for this patient's glomerular calcinosis, individual case reports in the literature have described resolution of calcinosis-associated nephrotic syndrome with treatment of the primary cause of hypercalcemia.

    View details for DOI 10.1053/j.ajkd.2005.10.030

    View details for Web of Science ID 000235189300026

    View details for PubMedID 16431246

  • Renal juxtaglomerular apparatus hyperplasia NEPHROLOGY DIALYSIS TRANSPLANTATION Troxell, M. L., Scandling, J. D., Sibley, R. K. 2005; 20 (10): 2282-2283

    View details for DOI 10.1093/ndt/gfh883

    View details for Web of Science ID 000232102800045

    View details for PubMedID 15941848

  • Renal tubular injury associated with anagrelide NEPHROLOGY DIALYSIS TRANSPLANTATION Rodwell, G. E., Troxell, M. L., Lafayette, R. A. 2005; 20 (5): 988-990

    View details for DOI 10.1093/ndt/gfh726

    View details for Web of Science ID 000229083800022

    View details for PubMedID 15728271

  • Mutant cadherin affects epithelial morphogenesis and invasion, but not transformation JOURNAL OF CELL SCIENCE Troxell, M. L., Loftus, D. J., NELSON, W. J., MARRS, J. A. 2001; 114 (6): 1237-1246


    MDCK cells were engineered to reversibly express mutant E-cadherin protein with a large extracellular deletion. Mutant cadherin overexpression reduced the expression of endogenous E- and K-cadherins in MDCK cells to negligible levels, resulting in decreased cell adhesion. Despite severe impairment of the cadherin adhesion system, cells overexpressing mutant E-cadherin formed fluid-filled cysts in collagen gel cultures and responded to hepatocyte growth factor/scatter factor (HGF/SF) that induced cellular extension formation with a frequency similar to that of control cysts. However, cells were shed from cyst walls into the lumen and into the collagen matrix prior to and during HGF/SF induced tubule extension. Despite the propensity for cell dissociation, MDCK cells lacking cadherin adhesion molecules were not capable of anchorage-independent growth in soft agar and cell proliferation rate was not affected. Thus, cadherin loss does not induce transformation, despite inducing an invasive phenotype, a later stage of tumor progression. These experiments are especially relevant to tumor progression in cells with altered E-cadherin expression, particularly tumor samples with identified E-cadherin extracellular domain genomic mutations.

    View details for Web of Science ID 000167952200022

    View details for PubMedID 11228167

  • Inhibiting cadherin function by dominant mutant E-cadherin expression increases the extent of tight junction assembly JOURNAL OF CELL SCIENCE Troxell, M. L., Gopalakrishnan, S., McCormack, J., Poteat, B. A., Pennington, J., Garringer, S. M., Schneeberger, E. E., NELSON, W. J., Marrs, J. A. 2000; 113 (6): 985-996


    Previous studies have shown that induction of cadherin-mediated cell-cell adhesion leads to tight junction formation, and that blocking cadherin-mediated cell-cell adhesion inhibits tight junction assembly. Here we report analysis of tight junction assembly in MDCK cells overexpressing a mutant E-cadherin protein that lacks an adhesive extracellular domain (T151 cells). Mutant E-cadherin overexpression caused a dramatic reduction in endogenous cadherin levels. Despite this, tight junction assembly was extensive. The number of tight junction strands observed by freeze-fracture electron microscopy significantly increased in T151 cells compared to that in control cells. Our data indicate that the hierarchical regulation of junctional complex assembly is not absolute, and that inhibition of cadherin function has both positive and negative effects on tight junction assembly.

    View details for Web of Science ID 000086312400010

    View details for PubMedID 10683147

  • Cadherin function in junctional complex rearrangement and posttranslational control of cadherin expression AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY Troxell, M. L., Chen, Y. T., Cobb, N., NELSON, W. J., MARRS, J. A. 1999; 276 (2): C404-C418


    The role of E-cadherin, a calcium-dependent adhesion protein, in organizing and maintaining epithelial junctions was examined in detail by expressing a fusion protein (GP2-Cad1) composed of the extracellular domain of a nonadherent glycoprotein (GP2) and the transmembrane and cytoplasmic domains of E-cadherin. All studies shown were also replicated using an analogous cell line that expresses a mutant cadherin construct (T151) under the control of tet repressor. Mutant cadherin was expressed at approximately 10% of the endogenous E-cadherin level and had no apparent effect on tight junction function or on distributions of adherens junction, tight junction, or desmosomal marker proteins in established Madin-Darby canine kidney cell monolayers. However, GP2-Cad1 accelerated the disassembly of epithelial junctional complexes and delayed their reassembly in calcium switch experiments. Inducing expression of GP2-Cad1 to levels approximately threefold greater than endogenous E-cadherin expression levels in control cells resulted in a decrease in endogenous E-cadherin levels. This was due in part to increased protein turnover, indicating a cellular mechanism for sensing and controlling E-cadherin levels. Cadherin association with catenins is necessary for strong cadherin-mediated cell-cell adhesion. In cells expressing low levels of GP2-Cad1, protein levels and stoichiometry of the endogenous cadherin-catenin complex were unaffected. Thus effects of GP2-Cad1 on epithelial junctional complex assembly and stability were not due to competition with endogenous E-cadherin for catenin binding. Rather, we suggest that GP2-Cad1 interferes with the packing of endogenous cadherin-catenin complexes into higher-order structures in junctional complexes that results in junction destabilization.

    View details for Web of Science ID 000078595500015

    View details for PubMedID 9950768