Colonic lipoma with florid vascular proliferation and nodule-aggregating appearance related to repeated intussusception.

A unique case of repeatedly intussuscepted colonic lipoma mimicking an epithelial tumor in a 50-year-old man is reported. The tumor was located in the ascending colon and was approximately 5 cm in diameter. Colonoscopic and barium-enema examinations suggested a huge epithelial tumor because of its nodule-aggregating appearance. In contrast, computed tomography examination showed a fatty element in the core of the lesion. The biopsy specimens suggested a primary angiomatous lesion because of its pronounced vascular proliferation. Because the presumed diagnoses based on the examinations were different, the preoperative diagnosis was not confirmed. The tumor was composed of intramural lipoma with a multiple polypoid mucosa overlay. This lesion was unique in that the lipoma appeared to be within the muscularis propria and the multiple polypoid appearance of its covering mucosa. The mucosal changes including florid vascular proliferation, fibromuscular obliteration and epithelial regeneration suggested a reparative process, with ischemic damage due to the effects of intussusception being the most likely event. It should be kept in mind that even a simple lipoma can have a unique appearance reminiscent of epithelial tumor when it repeatedly experiences intussusception.