Carcinomas of sweat glands: report of 60 cases.

Context: Several aspects of sweat gland carcinomas (incidence, classification, diagnosis, and behavior) have not been definitively clarified and need to be studied further.

Objective: The clinicopathologic findings of a large series of sweat gland carcinomas, collected during a period of 15 years, are presented.

Methods: Sixty sweat gland carcinomas (41 porocarcinomas, 3 syringomatous carcinomas, 8 ductal carcinomas, 5 adenoid cystic carcinomas, and 3 mucinous carcinomas) were analyzed histologically and immunohistochemically.

Results: Porocarcinomas were composed of eosinophilic and clear atypical cells arranged in solid-cystic lobular masses. These tumors were divided into 2 subgroups: horizontal porocarcinomas, showing a prominent intraepidermal component, and nodular porocarcinomas, which demonstrated predominant nodular growth. Syringomatous carcinomas presented keratinizing and nonkeratinizing cysts, dilated tubules (sometimes with a "tadpole" appearance), small neoplastic ducts, solid islands, and cellular cords. Ductal carcinomas were characterized by a prominent formation of tubules, solid islands, and cellular cords. Adenoid cystic carcinomas presented a characteristic pattern, showing basaloid monomorphous cells with moderately atypical nuclei, arranged in cribriform or solid islands and in tubular structures. Mucinous carcinomas were composed of moderately atypical cells with eosinophilic vacuolated cytoplasm, forming solid and cystic islands floating in large mucin pools. Immunohistochemically, cytokeratin was found in neoplastic cells in all cases, carcinoembryonic antigen was detected in 73% of cases, and actin-positive (myoepithelial) cells were not found.

Conclusions: Although numerous studies have been published in recent years, the histologic features, histogenesis, and classification of sweat gland carcinomas still remain controversial and need to be clarified by further studies.