Novel Histopathologic Features of Extramammary Paget's Disease in Metastatic Primary Cutaneous Apocrine Carcinoma to the Esophagus.

Primary cutaneous apocrine carcinoma (PCAC) is an exceptionally rare cutaneous malignancy originating from apocrine glands, occurring most commonly in the axilla and anogenital regions. It typically follows a slow-growing clinical course, although aggressive behavior has been documented in select cases. While local recurrence and regional metastasis are not uncommon in PCAC, instances of distant metastases are rare, with only a handful of cases reported, including involvement of the liver, bone, and lung. We present a unique case of PCAC with pagetoid features arising in the groin and metastasizing to the esophagus, a highly unusual presentation not well described in the existing literature. PCAC manifesting as extramammary Paget's disease (EMPD), characterized by single malignant epithelial cells scattered throughout the epidermis, represents a rare and diagnostically challenging variant. Its ability to mimic metastatic carcinomas from various organs necessitates thorough clinical and pathological correlation for accurate diagnosis. This case report aims to illuminate the potentially aggressive behavior of PCAC and emphasizes the need for long-term surveillance and awareness of its less typical presentations.