Essentially no difference in the copy number of COL1A1-PDGFB fusion gene was observed between dermatofibrosarcoma protuberans areas of classic dermatofibrosarcoma protuberans and dermatofibrosarcoma protuberans areas of fibrosarcomatous dermatofibrosarcoma protuberans (median PDGFB copy gain of 1.8 versus 1.7, respectively, P=0.36).
Recently, the COL1A1-PDGFB chimeric gene resulting from a reciprocal translocation, t(17;22), and/or a supernumerary ring chromosome, r(17;22), has been identified, not only in conventional dermatofibrosarcoma protuberans (DFSP) but also in areas of DFSP with progression to fibrosarcoma (so-called fibrosarcomatous transformation) (FS-DFSP).