Track: Case Reports

Abstract:

Sweat gland carcinoma with neuroendocrine differentiation (SCAND) is a newly proposed cutaneous apocrine/eccrine adnexal tumour with endocrine differentiation. It most commonly occurs in middle aged and elderly males, presenting as an erythematous nodule on the anterior trunk or inguinal region. Histologically, it is composed of neuroendocrine cells with solid nested, ribbon, and trabecular patterns described. It has the potential for aggressive biological behaviour with an increased risk of lymph node metastasis and distant systemic metastasis as its size increases. SCAND can be a histopathologic mimic of breast cancer and should be considered in the differential diagnosis in the appropriate clinical context. We report a case of SCAND presenting as an axillary lesion. A 41-year-old male developed a plaque-like skin lesion on his right axilla. Punch biopsy showed invasive carcinoma with neuroendocrine differentiation. The tumour cells were nested with moderate eosinophilic cytoplasm and enlarged nuclei with irregular contours, granular chromatin, and variably conspicuous nucleoli. The tumour cells expressed CK7, CK19, Ber-EP4 (patchy), CEA, EMA, GCDFP-15 (patchy), GATA3, ER, and PR; and lacked expression of CK20. Imaging studies excluded a breast primary lesion. On excision and axillary lymph node dissection, six of nineteen lymph nodes were positive for metastatic carcinoma. The tumor was limited to the dermis and subcutis. Breast tissue was not identified in the resection specimen. Diagnosis of SCAND is challenging due to overlapping histological and immunohistochemical findings with other entities. Recognition of SCAND is important as its biological behaviour can be aggressive and earlier diagnosis can improve outcomes.

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Stephen Smith