A Case of Dermatofibrosarcoma Protuberans with Fibrosarcoma Changes Developing into a Large Tumor.

For about a two-year duration, a patient (a 44-year-old male), had an 8×8×6cm, dome-shaped, elastic hard subcutaneous tumor on his central abdomen, close to his navel, which showed no adherence to the underlying muscles in a CT scan examination. We first performed a skin biopsy, and diagnosed DFSP. We then excised the whole tumor, and further fascia was additionally excised with a 2cm surgical margin. A histologic evaluation showed that the first biopsied tumor sample consisted of ordinary dermatofibrosarcoma protuberans (DFSP) composed of uniform spindle-shaped tumor cells in storiform patterns. The second sample, however, appeared to be compatible with fibrosarcoma in some areas, because it contained a dense proliferation of atypical spindle cells arranged in fascicular and herring-bone patterns. While immunohistochemical staining for CD34 was positive in the DFSP area, it was negative in the fibrosarcomatous area. No recurrence or metastasis was seen during the follow-up period of seven months. Furthermore, in this study we have reviewed and summarized the literature of ‘fibrosarcomatous variant of dermatofibrosarcoma protuberans’ in Japan. [Skin Cancer (Japan) 2002; 17: 246-250]