INTUSSUSCEPTED COLONIC LIPOMAS - LOSS OF FAT ATTENUATION ON CT WITH PATHOLOGICAL CORRELATION IN 10 CASES

Background: To determine if infarction and necrosis is the cause of th e confusing soft tissue density on CT within intussuscepting lipomas o f the colon. Methods: The clinical records, radiologic examinations, a nd pathologic specimens of all 13 cases of colonic Lipomas collected f rom 1988 to 1994 studied by CT and surgically resected were retrospect ively reviewed. Ten of these cases were associated with intussusceptio n; the CT attenuation of the lead point was graded according to its re lative fat/soft tissue density. Pathologic specimens were graded indep endently by a GI pathologist and graded according to the degree of inf arction/fat necrosis. Results: The lipomas ranged from 4 to 7 cm in di ameter (mean = 5 cm). Only one case with intussusception, and all thre e cases without, demonstrated pure fat attenuation on CT and demonstra ted pure fat histologically. One case demonstrated soft tissue attenua tion and corresponded with the most severely infarcted specimen histol ogically; two cases with similar but less:severe infarction/fat necros is corresponded with less than 25% fat attenuation. These latter three cases were originally misinterpreted as malignancies rather than lipo mas. Six cases maintained greater than 50% fat density and intermediat e amounts of infarction/fat necrosis. Conclusion: Lipomas may have an atypical appearance when intussuscepted due to varying degrees of infa rction/fat necrosis.