Congenital myxoid and pigmented dermatofibrosarcoma protuberans: a case report.

Dermatofibrosarcoma protuberans (DFSP) is a low-grade, mesenchymal, spindle cell tumor. In addition to the classical form characterized by a storiform pattern of tumor cells, pigmented (Bednar's tumor) and myxoid variants can be observed. Classical DFSP and Bednar's tumor are easily diagnosed. The myxoid variant represents a diagnostic challenge. Pigmented and myxoid variants are rare and thus far have never been reported in association in congenital DFSP. We came across a unique DFSP that was, at the same time, congenital, pigmented, and myxoid. The tumor was surgically excised with broad free margins and no recurrence. The differential diagnosis with other entities such as giant cell fibroblastoma, CD34-positive plaque-like dermal fibroma, superficial plaque-like CD34 DFSP, and neurocristic hamartoma is discussed. The recognition of this hybrid variant of congenital DFSP is important to avoid under- or overtreatment.