Presentation
The patient was a known case of gallbladder carcinoma who had undergone extended cholecystectomy and was under chemotherapy. Contrast CT was done for response evaluation.
Patient Data

CT shows non enhancing well defined fat attenuating area at the interatrial septum. Findings are consistent with diagnosis of lipomatous hypertrophy of the interatrial septum.
Case Discussion
Lipomatous hypertrophy of the interatrial septum is an incidental finding, usually asymptomatic and does not require any treatment. It is defined as a thickening of the interatrial septum of >20 mm thickness with fat attenuation sparing fossa ovalis 1. It is commonly seen in elderly obese patients and may be associated with corticosteroid therapy. If unaware of this condition this might be misinterpreted as thrombus or malignancy. Differential diagnosis includes cardiac lipoma.