Unusual presentation of Giant Dermatofibrosarcoma Protuberans

Abstract

Dermatofibrosarcoma protuberans (DFSP) is an uncommon, soft tissue sarcoma with a low metastatic potential but high rate of recurrence after surgical intervention. This tumor is characterized by a long history of slow growth. DFSP usually occurs on trunk and proximal extremities but rarely touches distal extremities such as hands, fingers, or foot below knees. We present a case of giant DFSP of the distal extremity, with a post-traumatic onset in childhood and a very long course. A 45-year-old patient presented with a tumoral lesion of the foot, evolving since 35 years with an onset at the age of 10 years, after a strong trauma of the 3rd toe. Physical examination revealed a reddish purple polynodular neoplastic lesion with a firm consistency. One of these nodular masses was ulcerated with areas of necrosis. The CT scan did not detect any bone involvement. Magnetic resonance imaging revealed a heterogeneously enhancing mass lesion on the dorsal aspect of the left forefoot. In depth, this mass invaded the dorsal interosseous muscles. The histopathological study was in favor of DFSP, with evidence of spindle-shaped tumor cells arranged in a storiform pattern. On immunohistochemistry (IHC), the cells expressed intense and diffuse CD34 and were negative for Desmin and S-100. The localization or occurrence of DFSP after a long period of trauma should not mislead the diagnosis. A careful histological study with IHC should be carried out in order to set up an appropriate treatment.