Giant Cardiac Lipoma: Refined Hypothesis Proposes Invagination from Extracardiac to Intracardiac Sites

Cardiac lipomas are rare and usually present as benign, encapsulated masses outside the heart; however, they can also be found within the atria. No single theory-including molecular genetic mutation-adequately explains why this occurs. Extensive career experience and broadened knowledge in embryology and cardiac physiology have helped us to develop a hypothesis based on invagination of extracardiac tumors. This report describes a vexing case of a giant right atrial lipoma, from 1985, in which the diagnosis was made incidentally during management of a patient's acute limb ischemia. In addition, we discuss the imaging and treatment of cardiac lipoma.