Gene Mutation Analysis in Five Cases of Dermatofibrosarcoma Protuberans Using Formalin-fixed, Paraffin-embedded Tissues

Fusion of the collagen type I a 1 (COL1A1) gene with the platelet-derived growth factor B-chain (PDGFB) gene has been pointed out in dermatofibrosarcoma protuberans. Various exons of the COL1A1 gene have been shown to be involved in the fusion with exon 2 of the PDGFB gene. We studied the breakpoints of the COL1A1 gene using formalin-fixed, paraffin-embedded tumour specimens from five patients with dermatofibrosarcoma protuberans (three reconfirmations and two new cases). Reverse transcriptase-PCR was performed using paraffin-embedded tissues. Nucleotide sequence analysis was carried out using the PCR products to identify the breakpoints. The COL1A1-PDGFB fusion transcripts were detected from the tumour specimens. Sequence analysis revealed that the ends of exons 18, 29, 38, 42 and 44 in the COL1A1 gene were fused with the start of exon 2 in the PDGFB. This study identified a novel COL1A1 breakpoint, namely, exon 44 of the COL1A1 gene. Detection of the aberrant fusion transcript using formalin-fixed, paraffin-embedded tumour specimens is useful as a diagnostic aid for dermatofibrosarcoma protuberans in cases where fresh or frozen samples of tumour tissue are not available.