"Acute" fat deposition in bowel wall submucosa: CT appearance

The deposition of submucosal fat in small and large bowel is known to occur in chronic processes such as inflammatory bowel disease, and has been assumed to reflect long disease duration. However, we have observed that submucosal fat deposition can occur in a short period of time.

Four patients were evaluated in whom serial CT examinations showed intramural fat deposition occurring within six months of a normal study. Confirmation of fatty deposition was made by Hounsfield unit measurement in all patients and by pathologic examination of bowel specimens in two patients.

All four patients received cytoreductive chemotherapy for treatment of lymphoma or leukemia prior to the development of fat deposition. In all patients, serial CT examination documented the occurrence of fat-attenuation bowel wall thickening that developed in a short time period (12, 36, 67, and 186 days). Three of the four cases were initially misinterpreted as wall thickening from other causes (intussusception or colitis). Pathologic examination of bowel in the two patients with the shortest time intervals confirmed the presence of mature fat confined to the submucosa.

These cases demonstrate that submucosal fat deposition in bowel wall is not limited to inflammatory bowel disease and other longstanding, chronic diseases; fatty infiltration can occur in a relatively short period of time, and is particularly likely to occur after cytoreductive therapy.