Sweat gland carcinoma ex eccrine spiradenoma.

We herein report two cases of sweat gland carcinoma that arose in association with eccrine spiradenoma. These lesions presented as enlarging masses that previously had been stable for many years. One produced widespread metastasis and death 5 months after diagnosis. Immunohistochemical studies demonstrated an antigenic relationship between the benign and malignant components of sweat gland carcinoma ex eccrine spiradenoma, but ultrastructural analyses showed a paucity of specialized differentiation. This neoplasm appears to display a range of microscopic appearances and has proven fatal in 20% of reported cases.