COL1A1 and dermatofibrosarcoma protuberans: Cytogenetically, more than 90% of DFSP cases are characterized with the collagen type I alpha 1 and platelet-derived growth factor B (COL1A1-PDGFB) fusion deriving from supernumerary ring r (17;22) or translocation t (17;22) (q22; q13) (5).