Dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare tumor but still the most common cutaneous sarcoma. DFSP is a tumor of fibroblastic origin, characterized by a slow, undermining and locally destructive growth pattern, which only rarely metastasizes. The clinical appearance, especially of smaller lesions, is often not characteristic, so that diagnosis is often made late and only on biopsy findings. The standard treatment of DFSP is excision with safety margins of 2 to 3 cm. If smaller margins are employed, the risk of local relapse is high. Surgically incurable or metastatic DFSP can be irradiated; the cells are generally radiation-sensitive. 90% of DFSP carry a chromosome translocation of 17 and 22, harboring a gene fusion, which results in a continuous activation of the PDGF beta signal transduction pathway. This finding led the way to a new molecular targeted therapy of DFSP using inhibitors of the PDGF beta pathway. The first drug to be registered for targeted treatment of locally advanced or metastasized DFSP is the multikinase inhibitor imatinib, showing a response of about 70% in clinical trials.