Bio


Dr. Kelsey Hirotsu is a Clinical Assistant Professor of Dermatology at Stanford University School of Medicine. She completed her fellowship in Mohs Micrographic Surgery & Dermatologic Oncology at the University of California San Diego. During fellowship she received additional training in cosmetic dermatology and laser procedures. She completed her dermatology residency at Stanford after graduating from Stanford University School of Medicine with a scholarly concentration in bioengineering. Dr. Hirotsu earned her Bachelor of Science degree in Chemical & Biomolecular Engineering at Johns Hopkins University.

Dr. Hirotsu has presented at national and international dermatology conferences. She is a regularly invited reviewer for peer-reviewed journals and has authored numerous publications in top dermatology journals.

Clinical Focus


  • Dermatologic Surgery
  • Mohs Micrographic Surgery
  • Micrographic Dermatologic Surgery

Academic Appointments


Professional Education


  • Board Certification: American Board of Dermatology, Micrographic Dermatologic Surgery (2022)
  • Internship: Scripps Mercy Hospital San Diego (2018) CA
  • Fellowship: UCSD Dermatology Fellowships (2022) CA
  • Board Certification: American Board of Dermatology, Dermatology (2021)
  • Residency: Stanford University Dermatology Residency (2021) CA
  • Medical Education: Stanford University School of Medicine (2017) CA

2024-25 Courses


Stanford Advisees


All Publications


  • Subclinical extension of cutaneous squamous cell carcinoma may predict poor outcomes in immunosuppressed patients treated with Mohs micrographic surgery: A retrospective cohort review. Journal of the American Academy of Dermatology Voller, L. M., Dominguez, J. L., Valencia, A., Maloney, N., Kibbi, N., Aasi, S. Z., Hirotsu, K. E. 2025

    View details for DOI 10.1016/j.jaad.2025.05.1448

    View details for PubMedID 40505738

  • Lymphovascular invasion is an independent predictor of metastasis and disease-specific death in cutaneous squamous cell carcinoma: a multicenter retrospective study. Journal of the American Academy of Dermatology Hirotsu, K. E., Aasi, S. Z., Samson, K. K., Zheng, C., Nazaroff, J. R., Voller, L. M., Ruiz, E. S., Ran, N. A., Granger, E. E., Koyfman, S. A., Vidimos, A. T., Carr, D. R., Shahwan, K. T., Carucci, J. A., Carter, J. B., Canueto, J., Girardi, F. M., Mangold, A. R., Srivastava, D., Brodland, D. G., Zitelli, J. A., Willenbrink, T. J., Wysong, A. 2025

    Abstract

    BACKGROUND: Lymphovascular invasion (LVI) is regarded as a high-risk feature of cutaneous squamous cell carcinoma (CSCC) but is currently absent from CSCC staging systems.OBJECTIVE: To assess whether LVI serves as an independent predictor of major poor outcomes in CSCC.METHODS: Twelve centers contributed to a multinational CSCC database. Clinical and pathologic risk factors, treatment, and patient outcomes were retrospectively collected. CSCCs were stratified based on LVI status. Tumors that developed major poor outcomes defined as nodal metastasis, in-transit metastasis, distant metastasis, and disease-specific death were identified.RESULTS: A total of 23,166 CSCCs were identified, 179 were LVI+ tumors (0.8%). LVI+ tumors had a higher cumulative incidence of major poor outcomes than those without LVI (33.5% vs. 3.2% at 3 years; overall cumulative incidence function p < 0.001). In an adjusted analysis, LVI+ tumors had an 82% increase in the rate of developing major poor outcomes when compared to LVI- tumors (subdistribution hazard ratio (SHR) = 1.82; p = 0.002). Notably, LVI+ low-stage BWH tumors (T1 or T2a) had a greater cumulative incidence of major poor outcomes compared to LVI- BWH low-stage tumors (20.7% vs. 1.61% at 3 years, overall cumulative incidence function p < 0.001).LIMITATIONS: Retrospective study design CONCLUSION: The presence of LVI in CSCC is a high-risk feature that is an independent predictor of metastasis and disease-specific death in both low and high BWH stage tumors.

    View details for DOI 10.1016/j.jaad.2025.04.029

    View details for PubMedID 40253009

  • A multicenter validation study of Mohs micrographic surgery vs wide local excision in primary high-stage cutaneous squamous cell carcinoma. Journal of the American Academy of Dermatology Wang, D. M., Ran, N. A., Granger, E. E., Koyfman, S., Vidimos, A., Wysong, A., Carr, D. R., Shahwan, K. T., Hirotsu, K. E., Carucci, J. A., Carter, J. B., Canueto, J., Girardi, F. M., Mangold, A. R., Srivastava, D., Nijhawan, R. I., Brodland, D. G., Zitelli, J. A., Willenbrink, T. J., Ruiz, E. S. 2025

    View details for DOI 10.1016/j.jaad.2025.04.010

    View details for PubMedID 40210096

  • Risk Factor Number and Recurrence, Metastasis, and Disease-Related Death in Cutaneous Squamous Cell Carcinoma. JAMA dermatology Ran, N. A., Granger, E. E., Brodland, D. G., Canueto, J., Carr, D. R., Carter, J. B., Carucci, J. A., Hirotsu, K. E., Koyfman, S. A., Mangold, A. R., Girardi, F. M., Shahwan, K. T., Srivastava, D., Vidimos, A. T., Willenbrink, T. J., Wysong, A., Ruiz, E. S. 2025

    Abstract

    Importance: Cutaneous squamous cell carcinoma (CSCC) risk stratification is central to management, and physicians rely on tumor staging systems to estimate risk. The Brigham and Women's Hospital (BWH) T staging system predicts risk based on 4 tumor risk factors (RFs). However, stage is not precisely associated with the number of RFs, as BWH stage T2b includes CSCCs with 2 and 3 RFs.Objective: To determine how RF number is associated with the risk of recurrence, metastasis, and disease-related death.Design, Setting, and Participants: This retrospective multination cohort study of CSCCs diagnosed between October 1, 1991, and July 19, 2023, was conducted at 12 centers in the US (10), Spain (1), and Brazil (1). Invasive CSCCs with confirmed negative margins longer than 14 days were included. Tumors were excluded if they were metastatic at presentation or received adjuvant therapy. Data were analyzed from October 2023 to August 2024.Interventions or Exposures: CSCCs were stratified by the number of the following RFs (0, 1, 2, 3, or 4): a diameter of 2 cm or larger, poorly differentiated histology, tumor extension beyond subcutaneous fat, and large caliber nerve invasion.Main Outcomes and Measures: Five-year cumulative incidences of local recurrence, nodal metastasis, distant metastasis, and disease-specific death.Results: A total of 16 844 CSCCs were included (5978 female individuals [35.5%]; median [IQR] age, 73.9 [65.7-81.8] years), with 0 (12 657 [75.1%]), 1 (2892 [17.2%]), 2 (1015 [6.0%]), 3 (225 [1.3%]) or 4 (55 [0.3%]) RFs. Median (IQ) follow up time was 33.6 (14.5-60.3) months. For local recurrence, the risk increased as the number of RF increased from 0 (1.7%; 95% CI, 1.5%-2.0%) to 1 (5.0%; 95% CI, 4.1%-5.9%) to 2 (8.8%; 95% CI, 7.0%-11.0%) to 3 (16.0%; 95% CI, 11.0%-22.0%) to 4 (33.0%; 95% CI, 19.0%-47.0%; P<.001 for between-group differences). This increase was also observed for nodal metastasis (0.6% [95% CI, 0.4%-0.7%] vs 3.6% [95% CI, 2.9%-4.4%] vs 11.0% [95% CI, 9.2%-13.0%] vs 20.0% [95% CI, 15.0%-26.0%] vs 28.0% [95% CI, 15.0%-42.0%], respectively; P<.001), distant metastasis (0.2% [95% CI, 0.1%-0.3%] vs 1.1% [95% CI, 0.7%-1.6%] vs 2.3% [95% CI, 1.4%-3.4%] vs 7.9% [95% CI, 4.6%-12.0%] vs 8.4% [95% CI, 2.6%-19.0%], respectively; P<.001), and disease-specific death (0.3% [95% CI, 0.2%-0.4%] vs 1.9% [95% CI, 1.4%-2.7%] vs 5.4% [95% CI, 4.0%-7.0%] vs 11.0% [95% CI, 6.7%-16.0%] vs 25% [95% CI, 12%-39%], respectively; P<.001). CSCCs with 3 RFs had higher cumulative incidences of local recurrence (1.6-fold), nodal metastasis (1.9-fold), distant metastasis (4.3-fold), and disease-specific death (1.9-fold) compared with those with 2 RFs.Conclusions and Relevance: The results of this cohort study suggest that the number of RFs is an indicator of risk, and among BWH T2b tumors, those with 3 RFs represent a higher risk subset.

    View details for DOI 10.1001/jamadermatol.2025.0128

    View details for PubMedID 40105853

  • riSCC: A personalized risk model for the development of poor outcomes in cutaneous squamous cell carcinoma. Journal of the American Academy of Dermatology Jambusaria-Pahlajani, A., Jeanselme, V., Wang, D. M., Ran, N. A., Granger, E. E., Canueto, J., Brodland, D. G., Carr, D. R., Carter, J. B., Carucci, J. A., Hirotsu, K. E., Karn, E. E., Koyfman, S. A., Mangold, A. R., Muradas Girardi, F., Shahwan, K. T., Srivastava, D., Vidimos, A. T., Willenbrink, T. J., Wysong, A., Lotter, W., Ruiz, E. S. 2025

    Abstract

    BACKGROUND: Cutaneous squamous cell carcinoma (CSCC) is a prevalent disease for which improved risk stratification strategies are needed.OBJECTIVE: To develop a novel prognostic model (herein "riSCC") for CSCC and compare riSCC performance to Brigham and Women's Hospital (BWH) and American Joint Committee on Cancer Staging 8th Edition (AJCC8) T staging systems.METHODS: Retrospective 12-center, multinational cohort study of CSCCs from 1991 to 2023. Clinical and pathologic risk factors, treatments, and outcomes were collected. Fine-Gray model was employed for each outcome with inverse probability of treatment weighting. A final model was trained for prospective use and estimation of hazard ratios.RESULTS: 23,166 localized CSCC tumors were included. riSCC prognostic model performed superiorly to American Joint Committee on Cancer 8th edition and Brigham and Women's Hospital T staging for all outcomes. At five years, the C-index for riSCC ranged from 0.74 for LR to 0.87 for DSD.LIMITATIONS: Retrospective study design CONCLUSION: riSCC prognostic model offers fine-grained risk estimates and improved stratification for important CSCC outcomes compared to T staging systems.

    View details for DOI 10.1016/j.jaad.2025.02.076

    View details for PubMedID 40024391

  • Identifying the Impact of Minor Risk Factors in Brigham and Women's Hospital Stage T1 Cutaneous Squamous Cell Carcinomas on Risk of Poor Outcomes: A Retrospective Cohort Study. Journal of the American Academy of Dermatology Shahwan, K. T., Walker, T. D., Tan, A., Ruiz, E., Ran, N., Granger, E. E., Koyfman, S., Vidimos, A., Wysong, A., Hirotsu, K. E., Carucci, J. A., Carter, J. B., Canueto, J., Girardi, F. M., Mangold, A. R., Srivastava, D., Brodland, D. G., Zitelli, J. A., Willenbrink, T. J., Carr, D. R. 2025

    Abstract

    BACKGROUND: While Brigham and Women's Hospital (BWH) T1 cutaneous squamous cell carcinomas (CSCCs) are overall low risk, a small subset develop poor outcomes.OBJECTIVE: To evaluate the impact of minor risk factors on poor outcomes in T1 tumors.METHODS: Data was collected retrospectively from 11 centers. Univariable and multivariable regression analyses were performed evaluating the impact of minor risk factors (moderate differentiation, diameter 1-2 centimeters, fat invasion, and small-caliber perineural invasion [PNI]) on poor outcomes. Cumulative incidence function (CIF) plots were created for time to poor outcomes by number of minor risk factors.RESULTS: 15,481 BWH T1 tumors were included, of which 90 (0.58%) developed major poor outcomes and 332 (2.1%) developed any poor outcome. Minor risk factors that were significant on multivariable analysis included moderate differentiation, diameter, and subcutaneous fat invasion. CIF plots demonstrated an increased risk of poor outcomes with presence of multiple minor risk factors; the risk of metastasis and major poor outcomes exceeded 5% in tumors with 3 minor risk factors.LIMITATIONS: Retrospective design, limited number of major poor outcomes.CONCLUSION: T1 tumors with multiple minor risk factors may be eligible for closer surveillance. Future staging systems should consider incorporating both major and minor risk factors.

    View details for DOI 10.1016/j.jaad.2025.02.052

    View details for PubMedID 40010504

  • 5-fluorouracil 5% cream for squamous cell carcinoma in situ: Factors impacting treatment response. Journal of the American Academy of Dermatology Lin, C. P., Kibbi, N., Bandali, T., Hirotsu, K., Aasi, S. Z. 2024

    Abstract

    BACKGROUND: Complete clinical response (CCR) rates for squamous cell carcinoma in situ (SCCis) treated with 5-fluorouracil (5-FU) 5% cream range from 27-85%. Factors associated with CCR are not well-established.METHODS: Retrospective review of biopsy-proven primary SCCis diagnosed between 5/1/2019-4/30/2020 and treated with 5-FU 5% cream. Disease status at follow-up was recorded, with treatment failure defined as persistent or recurrent disease.RESULTS: The study included 149 SCCis cases, including 33.6% (50/149) arising in the context of immunosuppression. Eighteen cases failed treatment (10 persistent disease, 8 recurrent disease). By tumor size, CCR was noted in 128/144 (88.9%) tumors measuring <2 centimeters in diameter and 3/5 tumors ≥2 centimeters (60.0%, p=0.051). By treatment duration, CCR was observed in 4/7 (57.1%) tumors treated for <2 weeks, 72/83 (86.7%), tumors treated for 2 to <4 weeks, and 55/59 (93.2%) tumors treated for ≥4 weeks (p=0.019). On multivariate analysis, treatment failure was significantly associated with shorter treatment durations (OR 0.26; p=0.007) and increasing tumor size (OR 2.40; p=0.037).CONCLUSIONS: Shorter treatment duration and larger lesion size were significantly associated with failure of 5-FU in SCCis. Immunosuppression and anatomic location were not significant factors, supporting 5-FU use for SCCis in the immunosuppressed population and highlighting its versatility irrespective of anatomic location.

    View details for DOI 10.1016/j.jaad.2024.10.066

    View details for PubMedID 39521136

  • Most cutaneous squamous cell carcinoma recurrences occur in the first three years after diagnosis: A multicenter retrospective cohort study. Journal of the American Academy of Dermatology Granger, E. E., Ran, N. A., Groover, M. K., Koyfman, S. A., Vidimos, A. T., Wysong, A., Carr, D. R., Shahwan, K. T., Hirotsu, K. E., Carucci, J. A., Carter, J. B., Canueto, J., Girardi, F. M., Mangold, A. R., Srivastava, D., Brodland, D. G., Zitelli, J. A., Willenbrink, T. J., Ruiz, E. S. 2024

    View details for DOI 10.1016/j.jaad.2024.06.072

    View details for PubMedID 38971189

  • Histopathologic Characterization of Incidental Lesions Encountered During Mohs Micrographic Surgery With MART-1 Immunohistochemistry. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.] Hirotsu, K. E., Kibbi, N., Rieger, K. E., Aasi, S. Z. 2023

    Abstract

    As the use of melanoma antigen recognized by T cells (MART-1) immunohistochemistry (IHC) with Mohs surgery increases for the treatment of melanoma in situ and invasive melanoma, surgeons should be aware of MART-1 staining patterns of incidental lesions often encountered on frozen sections. Lack of this knowledge can lead to unnecessary additional surgery, increased health care costs, and loss of valuable laboratory staff time and resources.To characterize the histopathologic features of incidental lesions encountered during Mohs surgery for melanoma. To review key diagnostic and differentiating features on hematoxylin and eosin staining (H&E) and MART-1 IHC of these lesions.A comprehensive review of frozen-section histopathology slides from Mohs cases with MART-1 IHC at our institution was conducted from 2021 to 2023.Incidental benign and malignant lesions were identified and characterized on H&E frozen sections and MART-1 IHC. Although such entities can share MART-1 staining characteristics with melanoma in situ or melanoma, distinguishing characteristics on H&E and lack of histopathologic criteria for melanoma on MART-1 IHC can be used to distinguish these incidental lesions from melanoma.Staining of frozen sections for Mohs micrographic surgery with H&E and MART-1 IHC together can differentiate common incidental benign and malignant cutaneous lesions from melanoma.

    View details for DOI 10.1097/DSS.0000000000004048

    View details for PubMedID 38064448

  • Association of histopathological grade with stage and survival in sebaceous carcinoma: a retrospective cohort study in the National Cancer Database. Journal of the American Academy of Dermatology Maloney, N. J., Zacher, N. C., Aasi, S. Z., Hirotsu, K. E., Zaba, L. C., Kibbi, N. 2023

    View details for DOI 10.1016/j.jaad.2023.07.1013

    View details for PubMedID 37532139

  • Online risk calculator and nomogram for predicting sentinel lymph node positivity in Merkel Cell Carcinoma. Journal of the American Academy of Dermatology Maloney, N. J., Aasi, S. Z., Kibbi, N., Hirotsu, K. E., Zaba, L. C. 2023

    View details for DOI 10.1016/j.jaad.2023.05.042

    View details for PubMedID 37244414

  • Comparison of clinicopathologic features, survival, and demographics in sebaceous carcinoma patients with and without Muir-Torre syndrome. Journal of the American Academy of Dermatology Maloney, N. J., Zacher, N. C., Hirotsu, K. E., Rajan, N., Aasi, S. Z., Kibbi, N. 2023

    Abstract

    Visceral malignancies in patients with Lynch syndrome behave less aggressively than in those without Lynch syndrome. The behavior of sebaceous carcinoma (SC) in Muir-Torre syndrome (MTS), a variant of Lynch syndrome, is incompletely investigated.Investigate features and survival of SC patients with and without MTS.Retrospective cohort study in the Surveillance, Epidemiology, and End Results 17 database from 2000-2019 of patients with SC. Patients were classified as MTS or non-MTS cases based on a threshold score of 2 on the Mayo MTS Risk Score.We identified 105 (2.8%) MTS cases and 3677 (97.2%) non-MTS cases. On univariate analysis, MTS patients were younger, had a higher proportion of tumors outside the head/neck, and had fewer high-grade tumors. On Kaplan-Meier analysis, MTS patients trended toward having better SC-specific survival. On multivariate Cox proportional hazards analysis adjusting for other covariates, MTS status was an independent predictor of worse overall survival. However, there was no association between MTS status and SC-specific survival.Given relatively high disease-specific survival in SC, our study may have been underpowered to detect a difference on Kaplan-Meier analysis.Our study suggests SC does not behave more aggressively in patients with MTS.

    View details for DOI 10.1016/j.jaad.2023.03.032

    View details for PubMedID 37003478

  • Positive surgical margins in sebaceous carcinoma: risk factors and prognostic impact. Journal of the American Academy of Dermatology Maloney, N. J., Aasi, S. Z., Hirotsu, K. E., Zaba, L. C., Kibbi, N. 2023

    View details for DOI 10.1016/j.jaad.2023.01.049

    View details for PubMedID 36907557

  • Acanthosis nigricans in the setting of severe pulmonary disease exacerbated by COVID-19 infection. JAAD case reports Hirotsu, K. E., Chiang, A., Bahrani, E., Cloutier, J. M., Rieger, K. E., Kwong, B. Y., Aleshin, M. 2022

    View details for DOI 10.1016/j.jdcr.2022.04.017

    View details for PubMedID 35529073

  • Histologic subtype of cutaneous immune-related adverse events predicts overall survival in patients receiving immune checkpoint inhibitors. Journal of the American Academy of Dermatology Hirotsu, K. E., Scott, M. K., Marquez, C., Tran, A. T., Rieger, K. E., Novoa, R. A., Robinson, W. H., Kwong, B. Y., Zaba, L. C. 2021

    View details for DOI 10.1016/j.jaad.2021.11.050

    View details for PubMedID 34875301

  • Complete remission from intralesional talimogene laherparepvec for regionally advanced Merkel cell carcinoma in an immunocompromised solid organ transplant patient. JAAD case reports Hirotsu, K. E., Hua, V., Tran, A. T., Morris, L., Reddy, S. A., Kwong, B. Y., Zaba, L. C. 2021; 13: 144-146

    View details for DOI 10.1016/j.jdcr.2021.05.005

    View details for PubMedID 34195326

  • Clinical Characterization of Mogamulizumab-Associated Rash During Treatment of Mycosis Fungoides or Sezary Syndrome. JAMA dermatology Hirotsu, K. E., Neal, T. M., Khodadoust, M. S., Wang, J. Y., Rieger, K. E., Strelo, J., Hong, E., Kim, Y. H., Kwong, B. Y. 2021

    Abstract

    Importance: Mogamulizumab is a monoclonal antibody against CCR4 approved for treatment for mycosis fungoides (MF) and Sezary syndrome (SS). Mogamulizumab-associated rash (MAR) is difficult to differentiate from cutaneous MF or SS, which can lead to unnecessary discontinuation of drug use because of concern for severe drug reaction or incorrect presumption of disease relapse or progression in the skin.Objective: To examine the most common clinical presentations of MAR in patients with MF or SS and the diagnostic and management challenges.Design, Setting, and Participants: This retrospective case series assessed patients from a multidisciplinary cutaneous lymphoma clinic and supportive oncodermatology clinic at a major academic referral center who had a diagnosis of MF or SS and received mogamulizumab from January 1, 2013, to January 1, 2020. Treatment was followed by new or worsening rash with skin biopsy results compatible with drug eruption determined by clinicopathologic correlation and molecular testing to exclude active malignant disease.Exposures: At least 1 dose of mogamulizumab.Main Outcomes and Measures: Mogamulizumab-associated rash was characterized by clinical features, including time to onset, clinical presentation, histopathologic features, and management approach.Results: The study included 19 patients with MF or SS who developed MAR (median age, 65 years; age range, 38-82 years; 10 [52.6%] male). Median time to MAR onset was 119 days (range, 56 days to 3.8 years). Patients with MAR exhibited 4 predominant clinical presentations: (1) folliculotropic MF-like scalp plaques with alopecia, (2) papules and/or plaques, (3) photoaccentuated dermatitis, and (4) morbilliform or erythrodermic dermatitis. The most common anatomical region involved was the head and neck, including the scalp. Histopathologic findings were variable and did not correspond to primary clinical morphologic findings. Immunohistochemistry and T-cell clonality ancillary testing were helpful to distinguish MAR from disease. Most patients with MAR (14 of 19) discontinued mogamulizumab treatment; however, no life-threatening severe cutaneous adverse drug reactions occurred, and the decision for drug therapy cessation was usually multifactorial. Four patients were treated again with mogamulizumab with no life-threatening drug-related events. Approaches to management of MAR include topical corticosteroids, systemic corticosteroids, and/or methotrexate.Conclusions and Relevance: This case series found that mogamulizumab-associated rash had a heterogeneous clinical presentation with variable and delayed onset in patients with MF or SS. Mogamulizumab-associated rash exhibited a predilection for the head and neck and was difficult to clinically distinguish from relapse or progression of disease. Recognition of the most common clinical presentations can help prevent unnecessary discontinuation of mogamulizumab treatment. The presence of MAR does not necessitate permanent discontinuation of or avoidance of retreatment with mogamulizumab.

    View details for DOI 10.1001/jamadermatol.2021.0877

    View details for PubMedID 33881447

  • An ulcerated violaceous nodule on the thigh. JAAD case reports Hirotsu, K. E., Kumar, A. M., Rieger, K. E., Chen, J. K. 2021; 9: 61–63

    View details for DOI 10.1016/j.jdcr.2021.01.011

    View details for PubMedID 33665278

  • Histopathologic Characterization of Mogamulizumab-associated Rash. The American journal of surgical pathology Wang, J. Y., Hirotsu, K. E., Neal, T. M., Raghavan, S. S., Kwong, B. Y., Khodadoust, M. S., Brown, R. A., Novoa, R. A., Kim, Y. H., Rieger, K. E. 2020

    Abstract

    Rash is one of the most common adverse events observed with mogamulizumab, an anti-C-C chemokine receptor 4 monoclonal antibody approved for previously treated mycosis fungoides (MF) and Sezary syndrome (SS). Given the nonspecific clinical presentations of this rash, histopathologic distinction from MF/SS is critical for informing clinical management. We performed a comprehensive characterization of the histopathologic findings in mogamulizumab-associated rash (MAR) with the integration of high-throughput sequencing of T-cell receptor (TCR) genes. Fifty-two biopsy specimens from 19 patients were evaluated retrospectively. Three major histologic reaction patterns were identified: spongiotic/psoriasiform dermatitis (33/52), interface dermatitis (11/52), and granulomatous dermatitis (8/52). Almost half of the specimens (21/52) showed at least 2 of these reaction patterns concurrently. Dermal eosinophils were not a consistent feature, being present in only half (27/52) of specimens and prominent in only 3. Features mimicking MF/SS, including lymphocyte exocytosis, lamellar fibroplasia, and adnexal involvement, were commonly seen but tended to be focal and mild. In 38/43 specimens with available immunohistochemistry, intraepidermal lymphocytes demonstrated a CD4:CD8 ratio ≤1 : 1. Low background levels of the patient's previously identified MF/SS-associated TCR sequence(s) were demonstrated in 20/46 specimens analyzed by high-throughput sequencing of TCR. We conclude that MAR may demonstrate diverse histologic features. Findings that may distinguish MAR from MF/SS include the inverted or normalized CD4:CD8 ratio within intraepidermal lymphocytes and demonstration of absent or nondominant levels of disease-associated TCR sequences. Correlation with the clinical findings and immunohistochemical and molecular characterization of the patient's MF/SS before mogamulizumab, when possible, may facilitate recognition of MAR.

    View details for DOI 10.1097/PAS.0000000000001587

    View details for PubMedID 32976123

  • Clinicopathologic characterization of enfortumab vedotin-associated cutaneous toxicity in patients with urothelial carcinoma. Journal of the American Academy of Dermatology Hirotsu, K. E., Rana, J. n., Wang, J. Y., Raghavan, S. S., Rieger, K. E., Srinivas, S. n., Fan, A. C., Kwong, B. Y., Novoa, R. A., Zaba, L. n. 2020

    View details for DOI 10.1016/j.jaad.2020.11.067

    View details for PubMedID 33301805

  • Treatment of Hypertrophic Granulation Tissue: A Literature Review. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.] Hirotsu, K., Kannan, S., Brian Jiang, S. I. 2019

    Abstract

    BACKGROUND: Hypertrophic granulation tissue (HGT) is an uncommon but a frustrating complication of wound healing. Given its low prevalence and often refractory nature, many treatment options have been explored.OBJECTIVE: No comprehensive review exists on HGT management in dermatology literature; thus, the authors hope to compile a review of available treatments.MATERIALS AND METHODS: An exhaustive key word search of 3 databases was performed for treatment of HGT. Results from these reports were summarized in this review.RESULTS: Methods of treatment included silver nitrate, topical steroids (n = 11), intralesional steroids (n = 55), steroid tape (n = 25), surgical removal, polyurethane foam dressing (n = 32), and pulsed-dye laser (n = 13).CONCLUSION: With all treatment methods, the cases and studies reported varying degrees of successful treatment with HGT reduction. Given the lack of published literature, it remains unknown whether the initial injury preceding HGT formation determines treatment modality success. For HGT refractory to silver nitrate, choice of treatment depends on accessibility, ease of use, cost, and location of the wound. Intralesional and topical steroids should both be considered. Polyurethane foam can be considered an adjunct treatment. If resources allow, laser treatment should also be considered.

    View details for DOI 10.1097/DSS.0000000000002059

    View details for PubMedID 31403535

  • Association of Antibiotic Resistance With Antibiotic Use for Epidermal Growth Factor Receptor Inhibitor-Related Papulopustular Eruption JAMA DERMATOLOGY Hirotsu, K., Dang, T. M., Li, S., Neal, J. W., Pugliese, S., Subramanian, A., Kwong, B. Y. 2019; 155 (7): 848–50
  • Association of Antibiotic Resistance With Antibiotic Use for Epidermal Growth Factor Receptor Inhibitor-Related Papulopustular Eruption. JAMA dermatology Hirotsu, K. n., Dang, T. M., Li, S. n., Neal, J. W., Pugliese, S. n., Subramanian, A. n., Kwong, B. Y. 2019

    View details for PubMedID 31017625

  • Cardiotoxicity associated with immune checkpoint inhibitors in cutaneous oncology. Journal of the American Academy of Dermatology Tabata, M. M., Choi, S. n., Hirotsu, K. n., Kwong, B. n., Soleymani, T. n. 2019

    View details for DOI 10.1016/j.jaad.2019.08.033

    View details for PubMedID 31437546

  • Geometric Deformations of the Thoracic Aorta and Supra-Aortic Arch Branch Vessels Following Thoracic Endovascular Aortic Repair VASCULAR AND ENDOVASCULAR SURGERY Ullery, B. W., Suh, G., Hirotsu, K., Zhu, D., Lee, J. T., Dake, M. D., Fleischmann, D., Cheng, C. P. 2018; 52 (3): 173–80

    Abstract

    To utilize 3-D modeling techniques to better characterize geometric deformations of the supra-aortic arch branch vessels and descending thoracic aorta after thoracic endovascular aortic repair.Eighteen patients underwent endovascular repair of either type B aortic dissection (n = 10) or thoracic aortic aneurysm (n = 8). Computed tomography angiography was obtained pre- and postprocedure, and 3-D geometric models of the aorta and supra-aortic branch vessels were constructed. Branch angle of the supra-aortic branch vessels and curvature metrics of the ascending aorta, aortic arch, and stented thoracic aortic lumen were calculated both at pre- and postintervention.The left common carotid artery branch angle was lower than the left subclavian artery angles preintervention ( P < .005) and lower than both the left subclavian and brachiocephalic branch angles postintervention ( P < .05). From pre- to postoperative, no significant change in branch angle was found in any of the great vessels. Maximum curvature change of the stented lumen from pre- to postprocedure was greater than those of the ascending aorta and aortic arch ( P < .05).Thoracic endovascular aortic repair results in relative straightening of the stented aortic region and also accentuates the native curvature of the ascending aorta when the endograft has a more proximal landing zone. Supra-aortic branch vessel angulation remains relatively static when proximal landing zones are distal to the left common carotid artery.

    View details for PubMedID 29400263

  • Promoting sunscreen use and sun-protective practices in NCAA athletes: Impact of SUNSPORT educational intervention for student-athletes, athletic trainers, and coaches JOURNAL OF THE AMERICAN ACADEMY OF DERMATOLOGY Ally, M. S., Swetter, S. M., Hirotsu, K. E., Gordon, J., Kim, D., Wysong, A., Donnelly, L., Li, S., Nord, K. M. 2018; 78 (2): 289-+

    Abstract

    Student-athletes (SAs) have an increased skin cancer risk on account of significant ultraviolet exposure; however, their sun-protective practices are suboptimal. A novel program, Stanford University Network for Sun Protection, Outreach, Research, and Teamwork (SUNSPORT), was designed to target SAs, coaches, and athletic trainers (ATs).To measure the impact of educational intervention on sun protection beliefs and practices of SAs.A survey of sun protection beliefs and practices was administered to National Collegiate Athletic Association athletes before and after intervention. SUNSPORT dermatologists educated SAs, coaches, and ATs regarding skin cancer risk and prevention methods. The main outcome was frequency of sunscreen use by SAs before versus after intervention.A total of 846 National Collegiate Athletic Association athletes were surveyed between September 23, 2012, and September 20, 2015. After intervention, significant increases were observed in sunscreen use 4 or more days per week by SAs (from 26% to 39% [P = .02]), SAs spoken to by their coach about sun safety (from 26% to 57% [P = .0001]), and SA recognition of higher skin cancer risk (from 54% to 67% [P = .04]).Intervention in only 1 West Coast university and no paired data.Following the SUNSPORT intervention, SAs were significantly more likely to use sunscreen, especially if encouraged by their coach. This study emphasizes that education directed to SAs, ATs, and coaches can improve sun-protective practices in SAs.

    View details for PubMedID 28993006

  • Changes in Geometry and Cardiac Deformation of the Thoracic Aorta after Thoracic Endovascular Aortic Repair Hirotsu, K., Suh, G., Lee, J. T., Dake, M. D., Fleischmann, D., Cheng, C. P. ELSEVIER SCIENCE INC. 2018: 83–89
  • Changes in Geometry and Cardiac Deformation of the Thoracic Aorta after Thoracic Endovascular Aortic Repair. Annals of vascular surgery Hirotsu, K., Suh, G., Lee, J. T., Dake, M. D., Fleischmann, D., Cheng, C. P. 2017

    Abstract

    BACKGROUND: Thoracic endovascular aortic repair (TEVAR) has dramatically expanded treatment options for patients with thoracic aortic pathology. The interaction between endografts and the dynamic anatomy of the thoracic aorta is not well characterized for repetitive physiologic stressors and subsequent issues related to long-term durability. Through three-dimensional (3D) modeling we sought to quantify cardiac-induced aortic deformation before and after TEVAR to assess the impact of endografts on dynamic aortic anatomy.METHODS: Eight patients with acute (n=4) or chronic (n=3) type B dissections, or chronic arch aneurysm (n=1), underwent TEVAR with a single (n=5) or multiple (n=3) Gore C-TAG(s). Cardiac-resolved thoracic CT images were acquired pre- and post-TEVAR. 3D models of thoracic aorta and branch vessels were constructed in systole and diastole. Axial length, mean, and peak curvature of the ascending aorta, arch, and stented lumens were computed from the aortic lumen centerline, delineated with branch vessel landmarks. Cardiac-induced deformation was computed from mid-diastole to end-systole.RESULTS: Pre-TEVAR, there were no significant cardiac-induced changes for aortic axial length or mean curvature. Post-TEVAR, the ascending aorta increased in axial length (2.7±3.1%, P<0.05) and decreased in mean curvature (0.38±0.05 0.36±0.05cm-1, P<0.05) from diastole to systole. From pre- to post-TEVAR, axial length change increased in the ascending aorta (P<0.02), mean curvature decreased in the arch and stented aorta (P<0.03), and peak curvature decreased in the stented aorta (P<0.05).CONCLUSIONS: TEVAR for a range of indications not only causes direct geometric changes to the stented aorta but also results in dynamic changes to the ascending and stented aorta. In our cohort, endograft placement straightens the stented aorta and mutes cardiac-induced bending due to longitudinal stiffness. This is compensated by greater length and curvature changes from diastole to systole in the ascending aorta, relative to pre-TEVAR.

    View details for PubMedID 28887263

  • Localized bullous pemphigoid in a melanoma patient with dual exposure to PD-1 checkpoint inhibition and radiation therapy. JAAD case reports Hirotsu, K. n., Chiou, A. S., Chiang, A. n., Kim, J. n., Kwong, B. Y., Pugliese, S. n. 2017; 3 (5): 404–6

    View details for PubMedID 28884139

  • Volumetric analysis demonstrates that true and false lumen remodeling persists for 12 months after thoracic endovascular aortic repair JOURNAL OF VASCULAR SURGERY CASES AND INNOVATIVE TECHNIQUES Suh, G., Hirotsu, K., Beygui, R. E., Dake, M. D., Fleischmann, D., Cheng, C. P. 2016; 2 (3): 101–4
  • Volumetric analysis demonstrates that true and false lumen remodeling persists for 12 months after thoracic endovascular aortic repair. Journal of vascular surgery cases and innovative techniques Suh, G. Y., Hirotsu, K., Beygui, R. E., Dake, M. D., Fleischmann, D., Cheng, C. P. 2016; 2 (3): 101-104

    Abstract

    A 62-year-old man underwent an elephant trunk procedure followed by thoracic endovascular aortic repair (TEVAR). Computed tomography angiography-based models were built to quantify volume of the whole aorta and true and false lumens preoperatively, before TEVAR, after TEVAR, and at follow-up at 3, 6, and 12 months. With TEVAR, descending aortic true lumen volume increased by 54%, then increased additionally by 60% during 12 months. The descending aortic false lumen volume regressed continuously for 12 months following TEVAR, with the most rapid rate from 6 to 12 months at 16 cm3/month. TEVAR immediately increased true lumen volume and continued to remodel the true and false lumens throughout the following 12 months.

    View details for DOI 10.1016/j.jvscit.2016.05.001

    View details for PubMedID 38827208

    View details for PubMedCentralID PMC11140378

  • Geometric analysis of thoracic aorta and arch branches before and after TEVAR Suh, G., Hirotsu, K., Zhu, Y. D., Lee, J., Dake, M., Fleischmann, D., Cheng, C. ELSEVIER SCIENCE INC. 2015: B129