COL1A1-PDGFB fusion in a pediatric Bednar tumor with 2 copies of a der(22)t(17;22).

We present a 10-year-old girl with a pure Bednar tumor (pigmented dermatofibrosarcoma protuberans) of the right shoulder. Cytogenetic analysis demonstrated 47 chromosomes with 2 copies of a derivative chromosome 22, der(22)t(17;22)(q22;q13). Fluorescence in situ hybridization (FISH) analysis demonstrated the COL1A1-PDGFB fusion on both der(22) chromosomes. By RT-PCR and sequencing, we observed a fusion of the COL1A1 exon 41 with PDGFB exon 2. This pure pediatric Bednar tumor in a child, like childhood dermatofibrosarcoma protuberans, had a linear structural abnormality rather than a ring chromosome that is more commonly encountered in adult Bednar and dermatofibrosarcoma protuberans tumors. The underlying molecular abnormality in this pediatric Bednar tumor is the same as in dermatofibrosarcoma protuberans.