Lipomatous infiltrates of the heart

Fatty masses of the heart usually arise in the interatrial septum and are uncommon. The autopsy files from LAC-USC Medical Center contain 15 such cases from 1952 through 1972. Although these masses are yellow and attain a large size, most are considered to represent lipomatous infiltrations rather than true lipomas since they usually lack encapsulation and do contain cardiac muscle in varying amounts. The lesion is most often associated with obesity. Surprisingly, even the large masses produce few clinical symptoms and none was suspected clinically, each being an incidental finding at necropsy. However, these masses do infiltrate the conduction system and can cause arrhythmias and sudden death. Echocardiography or other noninvasive techniques may bring attention to a lipomatous mass that may or may not be asymptomatic. This can result in a clinical dilemma in differential diagnosis and treatment since myxomas, rhabdomyomas, and sarcomas also arise in the interatrial septum.