Egpression of epithelial membrane antigen (EMA) was found in 11 of 57 (19%) cases of dermatoflbrosarcoma protuberans (DFSP). These tumors with EMA+ cells showed the following histological features: classical storiform pattern in all 11 cases, mygoid areas in three cases, Bednar tumor pattern in one case, and fibrosarcoma-like areas in one case. The EMA+ cells had a tendency to occur in moderately cellular and collagen-rich areas with parallel cell arrangement (4 cases) and in perivascular areas (3 cases). In such parts, a nuclear palisading and a wavy appearance of the nuclei were seen focally. One tumor contained perineurioma-like areas with whorled cell arrangement and EMA+ cells. The EMA+ cells were also found in ordinary storiform areas (6 cases), but here they were isolated and scarce. In two cases, the EMA+ cells were jugtaneural; therefore their origin from a sheath of preegisting nerves can not be egcluded. Egpression of EMA may reflect true perineurial cell differentiation in DFSP, as suggested previously in several ultrastructural and cytogenetic studies. The knowledge of occasional EMA pozitivity in DFSP is needed for a differential diagnosis between DFSP and other EMA+ soft tissue lesions.

        Key words: dermatoflbrosarcoma protuberans - epithelial membrane antigen (EMA) - perineurioma - soft tissue