The aim of this study is to investigate the immunohistochemical expression and distribution of WT1 (the transcription factor produced by the tumor suppressor gene of the same name) in a series of 114 cases of bland-looking mesenchymal spindle cell lesions of the dermis/subcutaneous tissues to evaluate its diagnostic utility in identifying DFSP. This evidence concerns the gene WT1 and dermatofibrosarcoma protuberans.