Mucinous eccrine sweat gland adenocarcinoma of the eyelid.

A firm, slow-growing cystic mass of the left upper eyelid developed in a 73-year-old man 5 years after a clinically diagnosed "sebaceous cyst" at the same site had been incised and drained. Histopathological examination disclosed a primary mucinous adenocarcinoma of eccrine sweat gland origin. The patient had no recurrence after 3.5 years of follow-up. Histochemical demonstration of sialomucin differentiates mucinous sweat gland carcinoma from other mucus-secreting adenocarcinomas, such as those arising from lacrimal gland tissue. Enzymatic histochemical analyses or ultrastructural studies are needed to distinguish between mucinous adenocarcinomas of eccrine origin and those of apocrine origin.