Composite tumor consisting of dermatofibrosarcoma protuberans and myxofibrosarcoma

A unique case of a composite tumor consisting of dermatofibrosarcoma protuberans and low-grade myxofibrosarcoma is described. The myxofibrosarcoma component formed 70% of the lesion volume. Both components protruded above the skin, and equally both infiltrated the subcutaneous tissue in the base of the lesion. The interface between them was mostly sharp but some small areas of gradual transition were also seen. Beside fibrosarcoma arising in the dermatofibrosarcoma protuberans, myxofibrosarcoma seems thus to be another possible manifestation of the change into a more malignant tumor rarely seen in the dermatofibrosarcoma protuberans.