Thomas M, Devouassoux-Shisheboran M, Lopez J, Descargues P, Gertych W, Caraivan I, You B, Péron J.
Gynecol Oncol Rep (2026)
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ABSTRACT
Background: Extramammary Paget's disease (EMPD) is a rare cutaneous in situ adenocarcinoma sometimes associated with invasive malignancy that may evolve to metastatic disease. HER2 alterations have been reported in aggressive cases and may be targetable.
Case presentation: We report a patient with metastatic vulvar EMPD with HER2 3+ score by immunohistochemistry (IHC) and ERBB2 amplification who progressed after local therapies, surgery, radiotherapy and trastuzumab ± paclitaxel. Off-label trastuzumab-deruxtecan (T-DXd) was started as second-line systemic therapy with marked extracranial and intracranial responses and acceptable toxicity.
Conclusion: This case supports consideration of HER2-directed antibody-drug conjugates in HER2-positive EMPD when standard options are exhausted.
Keywords: HER2 overexpression; Metastatic disease; Trastuzumab-deruxtecan; Vulvar EMPD.
