Abstract

Endocrine mucin producing sweat gland carcinoma (EMPSGC) is a rare, low-grade malignant tumor that was described in 1997 and is twice as common in women as in men. It is felt to originate from the glands of Moll, and is therefore encountered on the eyelid or periorbital skin. The morphological and immunohistochemical profile of this lesion is similar to either endocrine ductal carcinoma in situ or solid papillary carcinoma of the breast. Theoretically metastases from these breast lesions would be in the differential diagnosis, although in practice those lesions would not likely metastasize. In addition to metastases, the differential diagnosis may also include other benign or malignant adnexal neoplasms. Given the presence of extracellular mucin in some cases of EMPSGC, classic mucinous carcinoma, which also often occurs on periorbital skin, is a differential consideration. Some authors feel that EMPSGC is related to or has the potential to progress to classic mucinous eccrine carcinoma. We present a case of 66-year-old female with a right upper eyelid lesion located centrally on the free margin that was slow-growing, nodular, pink/red and displayed prominent vasculature. Biopsy revealed nests of tumor cells arranged in solid nodules with some extracellular mucin. The cells were uniform and round-to-oval with stippled nuclei. Only rare mitotic figures were identified. Immunohistochemistry showed strong cytoplasmic positivity with synaptophysin and NSE; CD56 was focally expressed on cytoplasmic membranes. P63 immunostaining revealed a partial loss of nuclear staining of myoepithelial cells. Chromogranin immunostaining was negative. Although bland in appearance, EMPSGC is a low-grade carcinoma and there are several reports of recurrences in the literature. Therefore, accurate diagnosis of this rare lesion is important in order to prompt complete excision.

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