A progression to dermatofibrosarcoma protuberans with a fibrosarcomatous component: A special reference to the chromosomal aberrations

Dermatofibrosarcoma protuberans (DFSP) with fibrosarcomatous areas (DFSP-FS ) is differentiated from ordinary DFSP by its unfavourable prognosis. We ca rried out sequential analysis of numerical chromosomal abnormalities in two cases of DFSP during their progression to metastatic disease with FS areas (DFSP-M-FS). They were compared with nine cases of ordinary DFSP and three cases of DFSP-FS, but without metastases. Numerical chromosomal changes we re examined by fluorescence in situ hybridization (FISH) using alpha-satell ite centromeric probes for chromosomes 1, 8, 11 and 17. Numerical imbalance s of chromosome 1 were not clarified. A gain of chromosome 8 was demonstrat ed in the two cases of DFSP-M-FS. A gain of chromosome 11 was observed in o ne of the two cases of DFSP-M-FS and in one case of DFSP-FS. A gain of chro mosome 17 was demonstrated in both metastatic tumours and in recurrent tumo urs in two cases of DFSP-M-FS, in addition to two cases of DFSP-FS and four cases of ordinary DFSP with recurrent tumours or large tumours. This study raised the hypothesis that a gain of chromosome 17 developed in recurrent or large-sized DFSP, which occurs in high-risk groups with the possibility of a progression to FS.