Localized fat collection adjacent to the intrahepatic portion of the inferior vena cava: a normal variant on CT.

We describe a normal focal collection of fat that has the appearance of a mass on CT scans. The fat is adjacent to the intrahepatic portion of the inferior vena cava and is contiguous to the fat around the subdiaphragmatic portion of the esophagus. This finding occurred in 11 (0.5%) of 2227 patients who had CT scans at our institution. The fat collections did not change in size or shape on follow-up CT scans obtained 2 to 29 months later (mean, 14 months). The localized fat collections were at the level of or above the confluence of the hepatic veins and the inferior vena cava, and were medial to the inferior vena cava. They were less than 22 mm in length, oval, and had attenuation values ranging from -113 H to -23 H on unenhanced CT scans. The collections enhanced slightly on scans obtained after contrast administration. T1-weighted (600/15) MR images obtained in three cases showed a high-intensity mass that was contiguous to high-intensity fat around the esophagus, medial to the intrahepatic portion of the inferior vena cava. Our experience suggests that a masslike fat collection adjacent to the intrahepatic portion of the inferior vena cava is a normal variant on CT scans and should not be mistaken for an abnormality.