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Case Reports

Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade cutaneous adnexal tumor with neuroendocrine and glandular differentiation. We report a case of a 57-year-old male who presented with a slowly enlarging telangiectatic nodule on the right upper eyelid. A shave biopsy was performed to rule out basal cell carcinoma. Histologic examination revealed a well-circumscribed dermal-based tumor composed of solid nests of basophilic epithelioid cells with round to oval nuclei, inconspicuous nucleoli, rare mitotic figures, and ductal/glandular differentiation. No necrosis was observed. Immunohistochemically, tumor cells were diffusely positive for INSM-1 and showed positivity for CK7, EMA, MOC-31, estrogen receptor (ER), and progesterone receptor (PR); CK20 was negative. These findings confirmed the diagnosis of EMPSGC. The tumor extended to the biopsy base and peripheral margin, prompting referral for Mohs micrographic surgery with oculoplastic consultation. This case underscores the importance of considering EMPSGC in the differential diagnosis of eyelid lesions, particularly those with a nodular appearance and slow progression. Recognition is crucial to ensure complete excision and avoid misdiagnosis with more aggressive adnexal carcinomas or cutaneous metastases.