Abstract
A man in his sixties had visited hospital because of an abdominal mass. A huge mass was detected in the abdomen, and therefore, he was admitted to our hospital. Computed tomography and magnetic resonance imaging revealed a tumor, 30 cm in size, with a mixture of adipose tissue and areas of calcification. Surgery was performed, and the tumor was found to be located in the retroperitoneal and properitoneal space. The resected specimen was 30 × 25 × 14 cm in size and weighed 5,500 g. Histopathologically, the adipose tissue component was diagnosed as well-differentiated liposarcoma and the calcification was diagnosed as low-grade osteosarcoma. The final diagnosis was a extraperitoneal well-differentiated liposarcoma with a low-grade osteosarcoma component. The patient has been well for 14 months after the surgery.
