Sonographic findings in intussusception caused by a lipoma in the muscular layer of the colon.

Lipomas of the gastrointestinal tract are uncommon tumors. Almost all gastrointestinal lipomas are submucosal or subserosal, and most are asymptomatic, although they may cause abdominal pain, bowel obstruction, and gastrointestinal bleeding. The diagnosis of gastrointestinal lipoma is usually not made before surgery. We present a case of colonic intussusception caused by a lipoma that was located in the muscular layer of the colon and was diagnosed preoperatively by sonography. The descending colon appeared edematous and thick. There was layering within the lumen of the descending colon, mimicking the target sign. At the distal end of the intussusception, there was a 4.7-cm, hyperechoic, rounded lesion with a smooth margin. Surgery revealed a polypoid mass originating from the splenic flexure and causing intussusception of the colon, and pathologic analysis confirmed the diagnosis of lipoma of the muscular layer of the colon.