[Pigmented dermatofibrosarcoma protuberans (Bednar's tumor)].

Pigmented dermatofibrosarcoma protuberans, first described by Bednar under the term storiform neurofibroma, is an infrequent neoplasm accounting for 1 to 5% of cases of dermatofibrosarcoma protuberans. Bednar's tumor is composed of spindle shaped cells arranged in a distinctive storiform or carthwheel pattern, and melanin-containing dendritic cells scattered within the tumor. The differential diagnosis with (non-pigmented) dermatofibrosarcoma protuberans is based on the presence of this population of pigmented cells. Two cases of pigmented dermatofibrosarcoma protuberans (Bednar's tumor) are reported here in, and a discussion follows on the clinicopathological features of this neoplasm and the different hypotheses on its histogenesis.