EPITHELIOID CELL HISTIOCYTOMA - A CLINICOPATHOLOGICAL AND IMMUNOHISTOCHEMICAL STUDY OF 8 CASES

Background: Epithelioid cell histiocytomas histologically resemble the intradermal form of Spitz nevus. Objective: We have studied eight patients with epithelioid cell histiocytoma. Methods: 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. Results: Epithelioid cell histiocytoma is characterized by proliferation of angulated epithelioid cells with abundant cosinophilic 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 leukocye antigen. Conclusion: Immunostainings are useful in the differential diagnosis of epithelioid cell histiocytoma from the intradermal form of Spitz nevus.