Dermatofibrosarcoma protuberans: an analysis of proliferative activity, DNA flow cytometry and p53 overexpression...

The aim of this study is to evaluate the degree and spectrum of malignancy of dermatofibrosarcoma protuberans (DFSP) in the aspect of proliferative activity, flow cytometric DNA analysis, and p53 immunoreactivity. Twenty-three tumors from 19 cases of DFSP including three cases of DFSP with fibrosarcomatous areas (DFSP-FS) were studied in comparison with its allied fibrohistiocytic tumors; that is, dermatofibroma (DF; 46 cases), fibrosarcoma (FS; four cases), and malignant fibrous histiocytoma (MFH; 11 cases). MIB-1 labeling index (LI) of DFSP was significantly higher than that of DF and was lower than those of FS and of MFH. In ordinary DFSP, the recurrent tumors exhibited significantly higher MIB-1 LI than that of the primary tumors, whereas 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-diploidy) was found in four recurrent and one primary tumors. Immunohistochemical p53 overexpression was found in three of 19 cases of DFSP which also showed higher proliferative activity and aneuploidy. All cases of DF were immunohistochemically negative for p53, but most of the cases of FS and MFH were positive. Although DFSP has been classified in a category of fibrohistiocytic 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.