Subcutaneous dermatofibrosarcoma protuberans on the breast

Dermatofibrosarcoma protuberans (DFSP) is a dermal spindle cell neoplasm of intermediate malignancy. It typically forms a brown indurated plaque on which firm nodules subsequently arise, sometimes with ulceration. Atypical DFSP presentations are not unusual, including atrophic, pedunculated, morphea-like and angioma-like forms. However, subcutaneous variant of DFSP that may either arise without dermal involvement or with minimal dermal involvement is very rare. A 36-year-old man presented with a palpable nodule without surface change around the right nipple. Microscopically, the neoplasm was composed of spindle cells with monomorphic storiform arrangement. The superficial part of the neoplasm was located in the subcutaneous tissue. Immunohistochemical staining showed strong cytoplasmic positivity for CD34, but not for factor XIIIa. Dermatologists should pay careful attention to these unusual variant of DFSP, which can be confused with other soft tissue tumors.