Vascular congenital dermatofibrosarcoma protuberans: a new histological variant of dermatofibrosarcoma protuberans.

We describe a case of congenital dermatofibrosarcoma protuberans (DFSP) that masqueraded as a vascular tumor both clinically and histologically. Based on the infiltrative growth pattern, presence of capillary-sized vessels, and spindle cell areas with slit-like vascular spaces and numerous thin-walled vessels at the periphery of the tumor, a kaposiform hemangioendothelioma was initially diagnosed. Strong diffuse CD34 positivity and the extension into the subcutaneous fat with a sieve-like effect prompted the fluorescence in situ hybridization analysis, which demonstrated a reciprocal t(17;22) translocation. According to our knowledge, this is the first report of a vascular histological variant of DFSP. This unique variant represents a potential pitfall for dermatopathologists and underlines the importance of cytogenetic diagnostics in unusual cases of DFSP.