Possible role of the collagen type I alpha 1–platelet‐derived growth factor beta chain fusion gene in the development of dermatofibrosarcoma protuberans with fibrosarcomatous transformation

Abstract Dermatofibrosarcoma protuberans with fibrosarcomatous transformation (DFSP‐FS) is a rare variant, with higher rates of recurrence and metastasis than DFSP. Detection of the collagen type I alpha 1 (COL1A1)–platelet‐derived growth factor beta chain (PDGFB) fusion gene is useful for the diagnosis of DFSP. In this letter, we report a case of DFSP‐FS, focusing on the expression of the COL1A1‐PDGFB fusion gene in the lesions. Increased expression of the COL1A1‐PDGFB fusion gene may be associated with fibrosarcomatous changes during the pathogenesis of DFSP.