Benign But Burdensome: When Lipomatous Hypertrophy Turns Pathologic With Superior Vena Cava Compression

A 71-year-old woman presented with dyspnea on exertion. Subsequent evaluation identified lipomatous hypertrophy of the interatrial septum (LHIS), which had findings of hypermetabolic activity owing to the presence of brown fat in the interatrial septum. LHIS is a rare condition and is typically considered to be a benign incidental finding. However, in the present case, LHIS resulted in the rare finding of compression of the superior vena cava.