Extramammary Paget's Disease of the Scrotum: A Case Report and Review of Literature.

Extramammary Paget's disease (EMPD) is a rare, intraepithelial adenocarcinoma that often presents with nonspecific dermatologic symptoms, leading to diagnostic delays. While surgical excision is the primary treatment for localized disease, metastatic EMPD is associated with poor prognosis and lacks a standardized first-line chemotherapy regimen. This report details a case of a 69-year-old male patient with EMPD of the scrotum, who was initially treated for carcinoma of unknown primary with six cycles of carboplatin/paclitaxel followed by consolidative radiotherapy. After progression of disease on restaging scans 12 months later, he received an additional six cycles of carboplatin/paclitaxel. Definitive diagnosis was obtained by scrotal biopsy, with convincing morphological and immunohistochemical correlation. With subsequent progression of disease, pembrolizumab was trialed despite a low combined positive score (CPS 5) due to prior chemotherapy-related toxicity. The patient survived 41 months after initiation of chemotherapy, exceeding the median overall survival of unresectable EMPD treated with chemotherapy in the literature. Our case highlights the diagnostic challenges of this rare entity. His relative success suggests carboplatin/paclitaxel as an effective first-line therapy for patients with metastatic EMPD or who are poor surgical candidates.