Adnexal carcinomas of the skin. I. Eccrine carcinomas.

The diagnostic identification of sweat gland carcinomas is hampered by their rarity and their histologic resemblance to various visceral tumors, leading to confusion with metastatic lesions. In this series, 14 cases of eccrine carcinoma in five male and nine female patients, ranging in age from 13 to 84 years, are described. Ten tumors strongly resembled infiltrating ductal adenocarcinomas of the breast, and were thus classified as ductal. Three had a prominent mucinous matrix, similarly explaining their categorization as mucinous carcinomas. Finally, one neoplasm was a classic eccrine porocarcinoma. Four patients with ductal eccrine carcinomas suffered metastasis, and a 50% mortality rate was observed among this group of ten cases. In contrast, only one of three mucinous carcinomas metastasized, although all of these lesions recurred locally, as did the single porocarcinoma. None of the latter four neoplasms proved fatal. The results of conventional special stains in these 14 cases are discussed, and histologic features that they shared, and which may be utilized in distinguishing eccrine carcinomas from benign sweat gland tumors, are presented.