S1 guidelines for dermatofibrosarcoma protuberans (DFSP) - update 2018.

While dermatofibrosarcoma protuberans (DFSP) is a rare cancer entity overall, it is nevertheless the most common type of cutaneous sarcoma. The tumor is of fibroblastic origin and characterized by slow, undermining and locally destructive growth. Metastatic spread is very rare. Given its nonspecific clinical appearance, diagnosis is frequently delayed. Biopsy and subsequent histopathology are key diagnostic tools. Standard treatment for primary tumors consists of complete excision with surgical margins of 1 to 2 cm. Smaller margins are associated with high local recurrence rates. Inoperable and metastatic DFSP may be treated with radiation therapy. Approximately 80-90 % of DFSP lesions harbor a fusion gene that results in continuous activation of the PDGF-β signaling pathway. Consequently, molecular targeted therapy inhibiting PDGF-β is an effective option for advanced (inoperable) and metastatic DFSP. The first agent to be approved for systemic treatment of DFSP is the multikinase inhibitor imatinib, showing objective response rates of about 50 % in clinical trials.