A case of a mesenteric lipoma in the transverse colon

A chest X-ray taken during a medical checkup for a 75-year-old man revealed a nodular shadow in the right middle lung field. Chest computed tomography (CT) for further examination showed an intra-abdominal tumor as an additional finding, and the patient was referred to our department. Contrast-enhanced CT revealed a tumor (16×10×5 cm) in the left upper to middle abdomen. The tumor had a clear border and uniform fat density inside. It compressed the stomach to the ventral side, but the patient had no subjective symptoms. Magnetic resonance imaging also showed the tumor contained a uniform fatty component inside, as well as no obvious non-fatty components. An intra-abdominal lipoma was suspected, but the possibility of a welldifferentiated liposarcoma could not be ruled out due to its size. During curative surgery, intraoperative findings revealed a soft tumor, weighing 612 g, with a well-defined border in the mesentery of the transverse colon. Pathological findings showed proliferation of mature adipocytes without malignancy. We report here this case of mesenteric lipoma, a rare intraabdominal tumor, and review the relevant literature.