Dermatofibrosarcoma protuberans: An analysis of proliferative activity, DNA flow cytometry and p53 overexpression with emphasis on its progression

The aim of this study is to evaluate the degree and spectrum of malignancy of dermatofibrosarcoma protuberans (DFSP) in the aspect of proliferative ac tivity, flow cytometric DNA analysis, and p53 immunoreactivity. Twenty-thre e tumors from 19 cases of DFSP including three cases of DFSP with fibrosarc omatous areas (DFSP-FS) were studied in comparison with its allied fibrohis tiocytic tumors; that is, dermatofibroma (DF; 46 cases), fibrosarcoma (FS; four cases), and malignant fibrous histiocytoma (MFH; 11 cases). MIB-1 labe ling index (LI) of DFSP was significantly higher than that of DF and was lo wer than those of FS and of MFH. In ordinary DFSP, the recurrent tumors exh ibited significantly higher MIB-1 LI than that of the primary tumors, where as the primary tumors showed almost the same proliferative activity of DF. DFSP-FS tended to have a higher proliferative activity than DFSP without FS -area (ordinary DFSP). In five of 19 cases of DFSP, aneuploidy (near-diploi dy) was found in four recurrent and one primary tumors. Immunohistochemical p53 overexpression was found in three of 19 cases of DFSP which also showe d higher proliferative activity and aneuploidy. All cases of DF were immuno histochemically negative for p53, but most of the cases of FS and MFH were positive. Although DFSP has been classified in a category of fibrohistiocyt ic tumor of intermediate malignancy, the recurrent DFSP, DFSP-FS, and DFSP with aneuploidy and/or p53 overexpression could be a subgroup of DFSP with more aggressive clinical behavior than ordinary primary ones.