A case of subcutaneous dermatofibrosarcoma protuberance

Abstract

A 68-year-old man presented with a complaint of a gradually growing subcutaneous tumor in the occipital region for 10 years. The tumor was 45×15 mm in size, and the epidermis did not show any color or atrophic changes. Magnetic resonance imaging showed that the tumor was located in the subcutaneous layer and revealed high intensity in short-T1 inversion recovery image (STIR). Histopathological examination revealed the presence of spindle-shaped tumor cells through the subcutaneous layer. As per the immunohistochemical examination, the tumor cells were CD34 (+). We performed RT-PCR using RNA extracted from frozen tumor tissue, and COL1A1-PDGFB fusion gene was detected. He was diagnosed with dermatofibrosarcoma protuberans (DFSP). Subcutaneous DFSP is a rare subtype of DFSP. In our case, the tumor cells had COL1A1-PDGFB fusion gene, suggesting that subcutaneous DFSP had the same origin as normal DFSP.