Colonic lipomas revisited on CT colonography

CT colonography (CTC) is growing in its utilization as a nationally approved colorectal cancer screening test. After colonic polyps, lipomas are the second most common colonic lesions and their accurate and rapid recognition are important.

This retrospective Institutional Review Board approved study was performed at two large academic university-based institutions. 1044 patients underwent CTC at Institution A from 2010 to 2018 and 1094 patients underwent CTC at Institution B from 2003 to 2015. All CTC examinations with at least one colonic lipoma in their report were evaluated by a fellowship-trained abdominal imaging radiologist. 47 CTC examinations containing 59 colonic lipomas were detected and included. Segmental location, sessile versus pedunculated morphology, multiplicity, average attenuation, and largest lesion diameter were evaluated. A review of the current literature on colonic lipomas is entailed.

The overall incidence of colonic lipoma was 2.2% in women and 2.3% in men. Mean age for detection of colonic lipomas on CTC was 66.9 years. Segmental locations of colonic lipomas include ascending colon (39%), transverse colon (19%), ileocecal valve (12%), cecum (12%), descending colon (10%), and rectosigmoid (8%). 9% of colonic lipomas were multiple, 42% were pedunculated, and 58% were sessile. The mean (range) size of detected lipomas was 19 (6-59) mm. The mean (range) attenuation was - 132 (- 41 to - 258) HU.

Most colonic lipomas are located in the ascending colon. Although they are typically solitary, just under 10% are multiple, and although they are most often sessile, slightly under half are pedunculated mimicking polyps. CTC detects smaller lipomas than optical colonoscopy.