Abstract
A 50-year-old man complaing of slight fever and left abdominal pain was referred to our hospital with a diagnosis of a left abdominal tumor by ultra sound in November 2010. When he was first seen, an ill-movable tumor with tenderness was palpated in the left lower quadrant of abdomen. Blood biochemical study revealed increased inflammatory reaction and mild anemia. Abdominal CT scan showed a fist-sized tumor located in the dorsal aspect of the descending colon and contained calcification. On MRI, the tumor showed high signal intersity on T1-and T2-weighted images. Laparotomy was performed with a diagnosis of retroperitoneal tumor. The retroperitoneal tumor and the descending colon were resected “en-bloc“. The resected tumor was 10.5×7.0×7.0 cm in size. The section was solid and there were white and yellow areas concomitantly. The histological diagnosis was retroperitoneal dedifferentiated liposarcoma containing liomyosarcoma and osteosarcoma components. Dedifferentiated liposarcoma containing lipomyosarcoma and osteosarcoma components is extremely rare.
