Colonic Lipoma

Colonic lipomas can be seen in up to ~4% of autopsy examinations of the colon. About 1/3 are located in the ascending colon, with incidence dropping the more distal you go down the colon.

They are the most most common benign tumors causing colo-colonic intussusception in adults. About 90% of colonic lipomas are submucosal. The rest are subserosal and related to the epiploic appendices.

Colonic lipomas are usually asymptomatic when smaller than 2 cm. Lesions larger than 2 cm are thought to be more likely to cause acute abdominal pain, changes in bowel habits, gastrointestinal bleeding (from ulceration of the colonic mucosa overlying the tumor), intussusception, or bowel obstruction. About 50% of patients with lipomas between 3 cm - 4 cm in diameter are symptomatic, while 75% of patients with lipomas larger than 4 cm are symptomatic.

Radiographs may reveal a focal radiolucency, but are usually not helpful. Contrast enema can also be nonspecific, revealing a smooth filling defect; however, changes in the lesion's shape and size on real-time fluoroscopy during peristalsis or with compression ("squeeze sign") can suggest the diagnosis.

CT or MRI can be diagnostic, by showing characteristic fat attenuation and intensity, respectively.

References

• Fernandez MJ, Davis RP, Nora PF. Gastrointestinal lipomas. Arch Surg. 1983 Sep;118(9):1081-3.
• Gollub MJ. Colonic intussusception: clinical and radiographic features. AJR Am J Roentgenol. 2011 May;196(5):W580-5.
• Gould DJ, Anne Morrison C, Liscum KR, Silberfein EJ. A lipoma of the transverse colon causing intermittent obstruction: a rare cause for surgical intervention. Gastroenterol Hepatol (N Y). 2011 Jul;7(7):487-90.