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.