PDGFB quantification is a useful tool in the diagnosis of dermatofibrosarcoma protuberans: a study of 10 cases

Summary Background.  Genetic aberrations involving the platelet-derived growth factor-β (PDGFB) gene and the collagen type 1 α1 (COL1A1) gene have been implicated in the pathogenesis of dermatofibrosarcoma protuberans (DFSP), a slow-growing and locally infiltrative dermal tumour. Aim.  To investigate the genetic rearrangements in 10 patients who presented with a clinical diagnosis of DFSP. Methods.  Total RNA was obtained from frozen sections and sections embedded in paraffin wax, and used for direct sequencing of the cDNA produced from reverse transcription (RT) PCR. The expression of PDFGB mRNA in each of these cases was also examined. Results.  Of the 10 samples examined, 9 had the COL1A1/PDGFB fusion transcript by DNA sequencing. The sequenced products showed that there was a fusion between the end of exons 6, 8, 29 (two cases), 38, 25 or 47 (three cases) and the start of exon 2 of the PDGFB gene. Quantitative RT-PCR identified all samples as having significantly higher expression of the PDGFB gene compared with normal skin or dermatofibroma. Conclusions.  Detection of the COL1A1/PDGFB fusion transcript may be important for the diagnosis of DFSP. Furthermore, relative PDGFB gene quantification by real-time PCR may also provide a good diagnostic tool when other methods fail to give conclusive results.