A case of pigmented dermatofibrosarcoma protuberans (Bednar tumor).

The present paper reports a 67-year-old male with pigmented dermatofibrosarcoma protuberans (Bednar tumor) on his right shoulder. The lesion had recurred twice. Clinically, the lesion was a reddish-brown, exophytic, multilobular, firm nodule with an irregular surface, which measured 6.4 x 4.2 cm. Histologically, the proliferated fibroblasts showed a cartwheel pattern and stained positively with CD34, similar to those of a common dermatofibrosarcoma protuberance. However, many melanin-bearing cells that were positive for the S-100 protein were found intermingled among the tumor cells. Based on these findings, we concluded that the clinical manifestations, level of malignancy, and cytological features, as well as the exception of melanin-bearing dendritic cells associated with pigmented dermatofibrosarcoma protuberans, suggest a common dermatofibrosarcoma protuberans. This supports the hypothesis that pigmented dermatofibrosarcoma protuberans is a pigmented variant of dermatofibrosarcoma protuberans. Thus, this type of tumor is not benign, but is an intermediate malignant tumor.