Skin metastasis of dermatofibrosarcoma protuberans with distinct morphological features, confirmed by COL1A1-PDGFB fusion gene analysis.

We discuss a metastatic dermatofibrosarcoma protuberans on the occiput of a 53-year-old man whose initial tumor appeared on his forehead 23 years previously. The pathology of the tumor that recurred at the initial site was fibrosarcomatous dermatofibrosarcoma protuberans, whereas the metastatic tumor was a pigmented dermatofibrosarcoma protuberans, the so-called Bednar tumor. Because both tumors possessed the identical chimeric COL1A1-PDGFB fusion gene, the metastatic nature of the occipital tumor was confirmed.