All Publications

  • A Subset of SMARCB1 (INI-1) Deficient Vulvar Neoplasms are Positive for Germ Cell Markers Hammer, P., McCluggage, W., Kolin, D., Howitt, B. SPRINGERNATURE. 2022: 755-756
  • A Subset of SMARCB1 (INI-1) Deficient Vulvar Neoplasms are Positive for Germ Cell Markers Hammer, P., McCluggage, W., Kolin, D., Howitt, B. SPRINGERNATURE. 2022: 755-756
  • Intravascular adenomyomatosis: a morphologic variant of intravenous leiomyomatosis associated with endometriosis and potential for misdiagnosis. Human pathology Fitzpatrick, M. B., Hammer, P. M., Yang, E. J., Howitt, B. E. 2021


    Intravenous leiomyomatosis (IVL) is a quasi-malignant smooth muscle tumor involving lymphatic and venous spaces of the myometrium. Rare cases of IVL with admixed endometrial glands and stroma have been described, termed intravascular adenomyomatosis. We report four additional cases of intravascular adenomyomatosis and expand the clinicopathologic features of these rare tumors. Patients were 39-45 years old and presented with symptoms of dysmenorrhea, postmenopausal bleeding, or pelvic mass. All cases were associated with endometriosis. Three cases comprised intravascular bland smooth muscle tumors with plexiform features, and in some foci the intravascular tumor contained endometrial type glands and stroma. In one case there was extensive (>10) foci of intravascular adenomyomatosis without evidence of associated smooth muscle neoplasm but did have an endometrial polyp with adenomyomatous features. None of the cases had nuclear atypia, increased mitotic activity, or tumor cell necrosis. The endometrial stromal components were positive for CD10 and negative or weakly positive for desmin by immunohistochemistry. Two cases underwent molecular testing for JAZF1 and PHF1 rearrangements with negative results. Three patients had no evidence of disease at the time of last follow-up, and one had persistent but stable disease 7 years after incomplete surgical removal and megestrol acetate treatment. Intravascular adenomyomatosis is a variant morphology rarely seen in IVL that lacks characteristic morphologic and molecular features of endometrial stromal sarcoma. Like IVL, prognosis is likely linked to completeness of surgical resection. In this study we found that intravascular adenomyomatosis is frequently associated with endometriosis, a novel finding to add to the literature on this rare IVL variant.

    View details for DOI 10.1016/j.humpath.2021.11.009

    View details for PubMedID 34856302

  • Black and Blue: Eyes and Dyes Sobel, R., Nirschl, J., Hammer, P., Sanchez, R., Pershing, S., Louie, C., Lin, J. OXFORD UNIV PRESS INC. 2021: 579
  • Molecular Classification of Endometrial Carcinomas with Long-Term Follow-up Hammer, P., Albro, J., Squires, C., Peters-Schulze, G., Sharp, B., Charu, V., Cessna, M., Howitt, B. SPRINGERNATURE. 2021: 691–93
  • 100 Years of the Pathology Medical Student Fellowship: Impacts on Undergraduate Education and Career Choices Hammer, P., Ireland, K., Houghton, D., Jaggers, A., Coleman, A., Snir, O., Troxell, M., Andeen, N. SPRINGERNATURE. 2021: 332–33
  • Well-differentiated lipomatous neoplasms with p53 alterations: A clinicopathologic and molecular study of eight cases with features of atypical pleomorphic lipomatous tumor. Histopathology Hammer, P. M., Kunder, C. A., Howitt, B. E., Charville, G. W. 2021


    Well-differentiated lipomatous neoplasms encompass a broad spectrum of benign and malignant tumors, many of which are characterized by recurrent genetic abnormalities. Although a key regulator of p53 signaling, MDM2, is characteristically amplified in well-differentiated liposarcoma, recurrent abnormalities of p53 itself have not been reported in well-differentiated adipocytic neoplasms. Here, we present a series of well-differentiated lipomatous tumors characterized by p53 alterations and histologic features in keeping with atypical pleomorphic lipomatous tumor (APLT).We reviewed the morphologic, immunohistochemical, and molecular genetic features of eight lipomatous tumors with p53 alterations. Four tumors arose in the thigh, and one case each arose in the shoulder, calf, upper back, and subclavicular regions; six tumors were deep/subfascial and two were subcutaneous. Relevant clinical history included two patients with Li-Fraumeni syndrome. Morphologically, all cases demonstrated well-differentiated adipocytes with prominent nuclear pleomorphism, limited mitotic activity, and no tumor cell necrosis. All cases were negative for MDM2 overexpression and amplification by immunohistochemistry and fluorescence in situ hybridization, respectively. By immunohistochemistry, p16 was diffusely overexpressed in all cases; seven tumors (88%) showed abnormal loss of Rb and p53. TP53 mutation or deletion was identified in 4 of 6 tumors evaluated by exon-targeted hybrid capture-based massively parallel sequencing; RB1 mutation or deletion was present in 5 of 6 cases.We present a series of eight well-differentiated lipomatous neoplasms characterized by p53 alterations in addition to Rb loss and histologic features of APLT. These findings suggest that impaired p53 signaling may contribute to the pathogenesis of APLT in a subset of cases.

    View details for DOI 10.1111/his.14593

    View details for PubMedID 34725851

  • 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

  • Differential Diagnosis of a Unique Vulvar Mass in an Adolescent. Obstetrics and gynecology Chow, S., Doyle, A., Hammer, P., Tyson, N. A. 2021


    Vulvar masses in adolescents have a broad differential diagnosis, yet few reports exist detailing masses of mammary origin.A nulliparous, healthy 16-year-old adolescent presented with a longstanding, ulcerated, 17-cm vulvar mass of unknown origin and pronounced inguinal lymphadenopathy. The patient underwent a left radical partial vulvectomy, with pathology revealing terminal duct lobular units consistent with polymastia.Differential diagnosis of a vulvar mass in an adolescent should include polymastia.

    View details for DOI 10.1097/AOG.0000000000004563

    View details for PubMedID 34735404

  • The utility and challenges of histopathologic evaluation in the diagnosis of nonmalignant skin ulcers. Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society Hammer, P., Latour, E., Bohnett, M. C., McKenzie, F., Korcheva, V. B., Mengden, S., White, K. P., Ortega-Loayza, A. G. 2020; 28 (2): 219-223


    Histopathologic evaluation of cutaneous ulcers is indicated when the clinical diagnosis is unclear or when ulcers have not responded to standard of care. Many nonmalignant skin ulcers lack specific histologic findings on biopsy and pose a diagnostic challenge. While the usefulness of skin biopsies to diagnose underlying malignancy in ulcerated lesions has been demonstrated in previous studies, their utility in the diagnosis of ulcers of other etiologies has not been reported. We conducted a retrospective study of 45 nonmalignant ulcer biopsies in a 3-year period to compare the histologic diagnosis with the final diagnosis. Additionally, we assessed the diagnostic concordance among three blinded dermatopathologists when reviewing these cases. The leading histologic diagnosis from each of the three observers agreed with the final clinical diagnosis, on average, for 29.6% of the cases (average pairwise kappa = 0.15). Inflammatory ulcers had the lowest concordance between the observers and final diagnosis with an average of 26.0% of cases (average pairwise kappa = 0.06). The observers agreed with each other for 35.6% of the cases (Fleiss' kappa = 0.32). The highest agreement among observers was in the vascular/vasculopathic category (50%, Fleiss' kappa = 0.44). Our results indicate that skin biopsies alone are useful in the evaluation of nonmalignant ulcers to rule out other conditions (e.g. neoplasm) but frequently not sufficient to establish a definitive diagnosis. Additional clinicopathologic correlation is necessary in the final assessment of nonmalignant ulcers to determine the diagnosis. Future research endeavors should explore alternative approaches to more efficiently diagnose nonmalignant skin ulcers.

    View details for DOI 10.1111/wrr.12780

    View details for PubMedID 31705777

  • Characterisation and diagnosis of ulcers in inpatient dermatology consultation services: A multi-centre study. International wound journal Haynes, D., Hammer, P., Malachowski, S. J., Kaffenberger, B., Yi, J. S., Vera, N., Calhoun, C., Shinohara, M. M., Seminario-Vidal, L., Trinidad, J. C., Keller, J. J., Ortega-Loayza, A. G. 2019; 16 (6): 1440-1444


    Accurate and prompt diagnosis of skin ulcers is critical to optimise management; however, studies in hospitalised patients are limited. This retrospective review of dermatologic consultations included 272 inpatients with skin ulcers between July 2015 and July 2018 in four U.S. academic hospitals. The median age was 54 years and 45% were male. In 49.3% of the patients, skin ulcers were considered the primary reason for admission. Ulcers of 62% were chronic and 49.6% were located on the lower extremities. Pyoderma gangrenosum (17.3%), infection (12.5%), and exogenous causes (11.8%) were the leading aetiologies; 12% remained diagnostically inconclusive after consultation. Diagnostic agreements pre-dermatology and post-dermatology consult ranged from 0.104 (n = 77, 95% CI 0.051-0.194) to 0.553 (n = 76, 95% CI 0.440-0.659), indicating poor-modest agreement. This study highlights the diagnostic complexity and relative incidences of skin ulcers in the inpatient setting.

    View details for DOI 10.1111/iwj.13211

    View details for PubMedID 31475449

  • Nipple leiomyoma: A rare neoplasm with a broad spectrum of histologic appearances. Journal of cutaneous pathology Hammer, P., White, K., Mengden, S., Korcheva, V., Raess, P. W. 2019; 46 (5): 343-346


    Cutaneous leiomyomas are rare benign smooth-muscle tumors. These lesions are distinguished based on their cell of origin and are subclassified as pilar leiomyoma, angioleiomyoma, and genital-type leiomyoma. Nipple leiomyoma is the least common genital-type leiomyoma, arising from the dartoic muscle cell of the nipple. Histologic examination of the lesion is necessary for definitive diagnosis, and these uncommon tumors can pose a diagnostic challenge. We describe herein a series of six nipple leiomyomas with a spectrum of histologic appearances.

    View details for DOI 10.1111/cup.13423

    View details for PubMedID 30663114