Clear cell eccrine carcinomas of the skin. A clinicopathologic study of nine patients

Sweat gland carcinomas with clear cell features are extremely rare neoplasms, with few well documented cases reported in the literature.

Data on nine patients with malignant eccrine adnexal neoplasms characterized by a prominent clear cell neoplastic component were studied. Immunohistochemical stains with a panel of antibodies against epithelial, stromal, and neural antigens were performed on five tumors and electron microscopic examination of one.

The tumors showed a spectrum of histologic features and growth patterns that ranged from well differentiated, low grade malignant neoplasms to poorly differentiated, highly aggressive, recurrent, and metastasizing tumors. All tumors contained a varied proportion of cells with abundant clear cytoplasm, similar to those seen in a group of benign eccrine adnexal neoplasms that have been variously designated as clear cell hidradenoma, nodular hidradenoma, clear cell myoepithelioma, and eccrine acrospiroma. Immunohistochemical stains on five tumors and ultrastructural examination in one were consistent with eccrine differentiation. Clinical follow-up of eight patients showed local recurrence in six, followed by metastases in three, despite local excision, radiation, and chemotherapy. Criteria for differentiating these tumors from their benign counterparts and from other types of malignant adnexal neoplasms and metastatic lesions are presented.

The findings indicate that clear cell eccrine carcinomas comprise a heterogeneous group of lesions that may range from locally recurring, low grade well differentiated tumors to highly aggressive, high grade tumors with a definite potential for uncontrollable local recurrence and metastasis. Wide surgical excision is recommended as the primary treatment for such neoplasms.