Malignant fibrous histiocytoma (MFH) originating in the retroperitoneal region is rarely encountered and its prognosis is very poor because of the local recurrence and metastases to other organs. A 74-year-old man was seen at the hospital because of a lt. lower abdominal swelling. Abdominal CTscan and magnetic resonance imaging (MRI) showed a tumor-like lesion at the lt. lower abdominal area, 10cm in size with marginal irregularity and inner density was heterogenous. Angiography from the lt. common iliac artery demonstrated a tumor stain. Under a suspicion of retroperitoneal sarcoma, an operation was performed. A resected tumor was 14×12×11cm in size and 490g in weight. With pathological findings, the tumor was diagnosed as MFH (storiform pleomorphic type)
Chest and abdominal CT scans performed 6 weeks from after the operation showed a local recurrence and multiple lung metastases. The patient died of respiratory faliure 16 weeks after the surgery. MFH has sometimes rapid cource like this case.