Dermatofibrosarcoma Protuberans Presenting as a Subcutaneous Mass in the Frontal Muscle of the Forehead

抄録

Dermatofibrosarcoma protuberans (DFSP) is a cutaneous fibrohistiocytic tumor of intermediate malignancy that typically arises in the dermis and subsequently infiltrates the subcutaneous tissue. Here, we present an extremely rare case of DFSP confined to an intramuscular lesion on the forehead. A 61-year-old female patient presented with a tender bicuspid subcutaneous mass on her forehead that had been gradually increasing in size for 10 years. The patient underwent surgical resection and pathological examination. Microscopically, cells with spindle-shaped nuclei and scant eosinophilic cytoplasm were arranged in a haphazard or monotonous pattern. However, no relationship was observed between the tumor and skin appendages. At the superficial margin, tumor cells infiltrated the surrounding frontalis muscle tissue, demonstrating typical DFSP morphology. In immunohistochemical studies, neoplastic cells were identified as anti-CD34 positive, which was a decisive diagnostic factor.