Sweat gland carcinoma: an easily confused skin malignancy.

Sweat gland carcinoma is a rare malignancy of the skin appendage. Surgeons and pathologists have limited experience with such tumor. Various classifications and diagnostic identifications lead to easy confusion with other metastatic lesions. Eight cases of sweat gland carcinoma were collected from 1020 cases of primary skin malignancies seen at the Veterans General Hospital-Taipei over the past 20 years. After a careful review of the clinical history and histopathology files, as well as immunohistochemical stains of CEA and S-100 protein, only three cases were proved to be sweat gland carcinomas, accounting for less than 0.3% of the primary tumors of skin. All three cases were eccrine histology in type. Two cases were CEA positive, and one case was positive with S-100 protein stain. Five cases which were excluded were negative to CEA and S-100 protein analysis. Thus it is suggested that sweat gland carcinoma should receive more accurate differential diagnosis from other skin malignancies, particularly metastatic tumors. Immunohistochemical analysis could help differential diagnosis. Treatment modalities of sweat gland carcinoma base mainly upon adequate wide surgical excision.