We report an angiosarcoma arising within a malignant endovascular papillary angioendothelioma (Dabska tumor) in soft tissue of the upper thigh/buttock of a 42-year-old woman. Although neoplastic progression within a vascular tumor of an existing low-grade lesion into DT has been described so far, we seem to be the first to report transformation of DT into an angiosarcoma.