A dedifferentiated liposarcoma of the anterior mediastinum.

Dedifferentiated liposarcoma was first described in 1979, and its definition has been recently extended. We found an undiagnosed anterior mediastinal mass in a 56- year-old man for whom we performed a complete tumor resection through median sternotomy. Microscopic examination revealed that the mass was primarily a low-grade, dedifferentiated liposarcoma, with a partial high-grade area. Occurrence of dedifferentiated liposarcoma in the anterior mediastinum is rare. We did not perform any adjuvant therapy. Three years after the surgery, the patient is alive without disease. In lipoma-like, well-differentiated liposarcoma cases, we should consider the possibility of dedifferentiated liposarcoma if a mild, atypical spindle cell component is found.