[Dermatofibrosarcoma protuberans: transition to fibrosarcoma]

We report on two patients suffering from dermatofibrosarcoma protuberans showing areas of fascicular fibrosarcoma. Whereas the mitotic rate was very low in the classic storiform parts of the tumor, the dedifferentiated areas presented an increased mitotic rate up to 10 to 15 mitoses/10 HPF. Metastases did not occur. Clinically, such a tumor may be treated like typical dermatofibrosarcoma protuberans as long as the sarcomatous component is small and not prevalent.