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Case Reports

Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, primary cutaneous low-grade adenocarcinoma characterized by neuroendocrine differentiation. EMPSGC usually occurs in elderly women, predominantly in the eyelid or periorbital regions. Its manifestation outside the head and neck area is uncommon, and its molecular landscape remains largely unexplored.

Here, we present a case of multifocal EMPSGCs in a 69-year-old woman, originating in the right upper chest and bilateral temples. Histopathologically, all three tumors exhibited basaloid adnexal neoplasms with solid and cystic architectures in the dermis, demonstrating immunoreactivity for CK7, GATA3, ER, TRPS1, INSM1, synaptophysin, and chromogranin, consistent with EMPSGC. Next-generation sequencing revealed a somatic mutation in NF2. Subsequent imaging studies with positron emission tomography and computed tomography scan revealed no locoregional or distant metastases. Mohs surgery effectively treated the three sites with no evidence of recurrence 15 months after the initial diagnosis.  To the best of our knowledge, NF2 mutation has not been previously documented in EMPSGCs. Furthermore, our case underscores the importance of recognizing rare extrafacial presentations of this tumor to prevent potential diagnostic challenges.