Objective To investigate expression of CD34 and platelet derived growth factor receptor ? (PDGFR-?) and pattern of DNA ploidy in dermatofibrosarcoma protuberans (DFSP), and to study their significance and relationship. Methods The expression of CD34 and PDGFR-? was detected by immunohistochemical SP method in paraffin-embedded specimens from 39 DFSPs and 30 dermatofibromas (DFs). The findings were quantitatively analyzed by image system. The pattern of DNA ploidy was detected by flow cytometry. Results The expression of CD34 and PDGFR-? in the DFSPs was higher than that in the DFs (P