5. Endocrine mucin producing sweat gland carcinoma

Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is an uncommon low-grade carcinoma with a predilection for the eyelid. Only 18 other cases have been reported in the literature to date. Here, we describe three cases of EMPSGC. They occurred in the right medial canthus of a 69-year-old woman, in the left lateral canthus of a 36-year-old man and in the left lower eyelid of a 53-year-old woman. Histologically, they were well circumscribed, typically multinodular tumours with solid or partially cystic nodules, frequently showing areas of papillary architecture with fibrovascular areas. The tumour cells showed positive staining for NSE, chromogranin, synaptophysin, CK7, CEA, ER and PR. The intracytoplasmic and extracellular mucin was positive with DiPAS. Myoepithelial cells did not stain with calponin, smooth muscle actin, S100 and p63, supporting the notion that EMPSGC is an invasive carcinoma. In the largest case series to date it was observed that 50% of EMPSGC had coexisting invasive mucinous adenocarcinoma on histology, suggesting that EMPSGC is a precursor to invasive mucinous adenocarcinoma. The prognosis of EMPSGC, even in cases associated with invasive mucinous carcinoma, is favourable, but longer follow-up is needed. Patients with EMPSGC should be closely followed clinically as mucinous carcinoma has well-documented metastatic potential.