This is a retrospective pathological and immunohistochemical study of 38 cases of dermatofibrosarcoma protuberans. It is a rare dermal and subcutaneous spindle cell tumor which may be difficult to diagnose. We tested the value of the CD34 antibody and compared this series with 15 fibrous histiocytomas and II neurofibromas. Thirty-one dermatofibrosarcoma protuberans were positive for CD34 and 7 were negative. All the fibrous histiocytomas were negative. Nine neurofibromas were positive with variable expression of CD34 antigen. The CD34 antibody seems to be a sensitive marker to differentiate dermatofibrosarcoma protuberans from fibrous histiocytoma. It is specific for the dermatofibrosarcoma protuberans in the context of differential diagnosis between these two tumors. The role of immunohistochemical staining remains useful within the anatomoclinical context.