Endocrine Mucin Producing Sweat Gland Carcinoma with Metastasis to Parotid Gland: Not as Indolent as Perceived?

Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSCG) is a rare, low-grade cutaneous adnexal neoplasm with evidence of neuroendocrine differentiation, predominantly involving the eyelids of elderly. It has a striking resemblance to solid papillary carcinoma of breast which similarly displays neuroendocrine features. EMPSGC is considered a precursor of cutaneous mucinous carcinoma, and the term "mucinous carcinoma" is also recommended for hybrid lesions which reveal an invasive mucinous component associated with EMPSGC. While local recurrences are well- documented in EMPSGC, metastases had not been encountered until very recently; two reports in the past year have described metastases from eyelid EMPSGC to the parotid gland after a prolonged interval from the primary presentation. We report the case of a 78-year-old male with eyelid EMPSGC metastatic to the parotid gland nine years after excision of the primary tumor, which had initially been diagnosed as a poorly differentiated carcinoma. Development of metastasis after a prolonged interval is similar to both the previously described cases, and emphasizes the need to reevaluate the stated indolent nature of this neoplasm. It also aims to draw attention of pathologists to this uncommon tumor of the eyelid which is often misdiagnosed on primary presentation.