Dedifferentiated solitary fibrous tumor of thoracic cavity.

Solitary fibrous tumor (SFT) is a mesenchymal tumor characterized by fibroblast-like tumor cells, thick collagen bands, a hemangiopericytoma-like branching vascular pattern and CD34 expression of tumor cells.1 Although some cases show malignant behavior, most of the cases are benign and have histologically bland-looking tumor cells. Rarely, highly pleomorphic sarcoma arises within a primary or recurrent SFT having typical histologic features. This is a phenomenon similar to that seen in dedifferentiated liposarcoma. Dedifferentiated SFT (DSFT) is rare, with less than 30 cases reported worldwide,2,3,4,5,6 and it has not been previously reported in Korea. Here, we present a case of DSFT.