Application of COL1A1-PDGFB fusion gene detection by fluorescence in situ hybridization in biopsy tissue of dermatofibrosarcoma protuberans.

Several uncommon variants of dermatofibrosarcoma protuberans (DFSP) and the limitations of small biopsies render pathological diagnosis difficult. The aim of this study was to analyze the utility of fluorescence in situ hybridization (FISH) in the detection of the collagen type I-α1/platelet derived growth factor-β (COL1A1-PDGFB) fusion gene in biopsies of DFSP. Twenty-three consecutive biopsy specimens of DFSP were reviewed for clinicopathological features and examined with the COL1A1-PDGFB fusion probe and PDGFB break-apart probe using FISH analysis. The 23 tumor samples consisted of 11 males and 12 females (mean age at diagnosis, 37 years; range, 14-75 years). Eighteen conventional DFSP, one Bednar tumor, two myxoid DFSP and two fibrosarcomatous DFSP samples were included in the group. Strong and extensive CD34 expression was observed in 19 of 23 cases (83%). Twenty-one cases (91%) were positive for both the COL1A1-PDGFB fusion signal and the PDGFB break-apart signal. This is one of the few studies to demonstrate the value of FISH analysis of the COL1A1-PDGFB gene, which could validate complicated and suspected diagnoses in the routine biopsy of DFSP.