Vulvar sweat gland carcinomas.

Sweat gland carcinomas constitute less than 10% of all malignant tumors of the vulva, including those associated with extramammary Paget's disease (EPD). The histopathologic diagnosis of vulvar sweat gland carcinomas is difficult because of their rarity; their resemblance to metastatic carcinomas of the internal female genitalia, kidneys, and other sites; and their diversity of microscopic appearances. We report five examples of vulvar sweat gland carcinomas, two of which were associated with EPD. The other tumors included one example each of ductal eccrine adenocarcinoma, eccrine porocarcinoma, and clear cell hidradenocarcinoma. The clinical behavior of these neoplasms is correlated with their histologic types; we also discuss differential diagnosis and treatment recommendations.