Metastatic Bednar tumor (pigmented dermatofibrosarcoma protuberans) with fibrosarcomatous change: a case report

Bednar tumor (pigmented dermatofibrosarcoma protuberans) is a variant of dermatofibrosarcoma protuberans (DFSP) that constitutes 5% of all DFSP and has a very low rate of distant metastases. We encountered a rare case of Bednar tumor with multiple different distant metastases. A 51-year-old man, who had had a history of mass resection in his left shoulder 4 years previously, was referred to our institution, complaining of a recurrence of the shoulder mass. The histological diagnosis of primary tumor was Bednar tumor, and he underwent resectional surgery for the recurrent lesion. A second local relapse, lung metastasis, retroperitoneal metastasis, and metastasis to the sigmoid colon have occurred. The recurrence lesion and all metastatic lesions were resected surgically. The histological features of all specimens showed fibrosarcomatous change. Seven months after the last surgical resection, the tumor recurred and the patient died of multiple abdominal metastases 10 years after the first surgical treatment.