Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare low-grade primary cutaneous adnexal neoplasm with a predilection for the periorbital or malar skin. EMPSGC is thought to be a precursor to mucinous carcinoma of the skin (MCS). Multicentric EMPSGC and/or MCS is extremely rare, with few reports describing 2-3 lesions in individuals. Herein, we report a 55-year-old woman with an 8-year history of 5 lesions of EMPSGC and MCS on the face. The patient was diagnosed with MCS on her left chin two years prior to initial presentation in our clinic, which was treated by Mohs micrographic surgery (MMS). A new reddish shiny papule appeared on her right chin. A biopsy showed basaloid solid and cystic nodules occupying the dermis, with associated extracellular mucin in the tumor lobules, exhibiting overlapping features of MCS and EMPSGC. A systemic workup showed no metastases nor other primary lesions, pancreatic intraductal papillary mucosal neoplasms were detected. Four years later, another biopsy from the right lateral canthus showed EMPSGC; the subsequent MMS procedure revealed features more typical of MCS. In the next 3 years, new histopathologically confirmed EMPSGC lesions sequentially occurred on the right cheek and the left lower eyelid, both treated with MMS. The tumors were positive for EMA and CEA stains. Chromogranin was variably positive. P63 stains highlighted the peripheral cells of the tumor islands, suggesting the presence of an in-situ lesion. Although the mechanism underlying this multicentric and asynchronous presentation is unknown, this case suggests the possibility of a germline genetic variant.