CLEAR-CELL ECCRINE CARCINOMAS OF THE SKIN - A CLINICOPATHOLOGICAL STUDY OF 9 PATIENTS

Background. Sweat gland carcinomas with clear cell features are extrem ely rare neoplasms, with few well documented cases reported in the lit erature. Methods. Data on nine patients with malignant eccrine adnexal neoplasms characterized by a prominent clear cell neoplastic componen t were studied. Immunohistochemical stains with a panel of antibodies against epithelial, stromal, and neural antigens were performed on fiv e tumors and electron microscopic examination of one. Results. The tum ors showed a spectrum of histologic features and growth patterns that ranged from well differentiated, low grade malignant neoplasms to poor ly differentiated, highly aggressive, recurrent, and metastasizing tum ors. All tumors contained a varied proportion of cells with abundant c lear cytoplasm, similar to those seen in a group of benign eccrine adn exal neoplasms that have been variously designated as clear cell hidra denoma, nodular hidradenoma, clear cell myoepithelioma, and eccrine ac rospiroma. Immunohistochemical stains on five tumors and ultrastructur al examination in one were consistent with eccrine differentiation. Cl inical follow-up of eight patients showed local recurrence in six, fol lowed by metastases in three, despite local excision, radiation, and c hemotherapy. Criteria for differentiating these tumors from their beni gn counterparts and from other types of malignant adnexal neoplasms an d metastatic lesions are presented. Conclusions. The findings indicate that clear cell eccrine carcinomas comprise a heterogeneous group of lesions that may range from locally recurring, low grade well differen tiated tumors to highly aggressive, high grade tumors with a definite potential for uncontrollable local recurrence and metastasis. Wide sur gical excision is recommended as the primary treatment for such neopla sms.