[A Case of Retroperitoneal Atypical Spindle Cell Lipomatous Tumor].

A 74-year-old man visited our clinic for treatment of a retroperitoneal tumor that had enlarged gradually. We performed surgical resection of the tumor because we suspected retroperitoneal liposarcoma radiographically. The histopathological diagnosis was an atypical spindle cell lipomatous tumor. No signs of recurrence or metastasis have been observed for one year after the operation.