Granular Cell Variant of Atypical Fibroxanthoma.

We report a case of atypical fibroxanthoma of the ear in which the dominant part of the tumor has granular cell appearance. Areas identical to conventional atypical fibroxanthoma were present only at the lateral infiltrating borders. Histologically the granular cells resembled those of the classical granular cell tumors but exhibited significant pleomorphism and a high mitotic rate. Immunostains for vimentin, CD68 and NK1/C3 were positive but for S-100, HMB-45, myogenic and epithelial markers were negative. The predominance of the granular cells in an atypical fibroxanthoma supports the concept that a small subset of tumors with granular cell phenotype are of nonneural origin.