Epithelioid cell histiocytoma. A clinicopathologic and immunohistochemical study of eight cases.

Abstract

Epithelioid cell histiocytomas histologically resemble the intradermal form of Spitz nevus. We have studied eight patients with epithelioid cell histiocytoma. In addition to the routine stains, histologic sections were prepared by immunohistochemical techniques for S-100 protein, HMB-45, vimentin, alpha 1-antitrypsin, and common leukocyte antigen. Epithelioid cell histiocytoma is characterized by proliferation of angulated epithelioid cells with abundant eosinophilic cytoplasm. Immunostaining for S-100 protein and HMB-45 were negative. The majority of cells had positive reactions to staining for vimentin and alpha 1-antitrypsin. Approximately 20% to 25% of cells also gave positive reactions to common leukocyte antigen. Immunostainings are useful in the differential diagnosis of epithelioid cell histiocytoma from the intradermal form of Spitz nevus.