A Cadaveric Case Report of a Rare Atrial Septal Lipoma

Primary cardiac tumors (PCTs) are rare and include myxomas, papillary fibroelastomas, rhabdomyomas, and lipomas. Lipomatous hypertrophy of the atrial septum (LHAS) is a benign condition associated with aging and obesity that is marked by fat accumulation in the interatrial septum and is caused by hyperplasia of adipose cells. In contrast, lipomas are characterized as soft masses of fat that are encapsulated by thin, fibrous tissue. True cardiac lipomas are rare and can present a diagnostic dilemma. Cardiac lipomas are generally asymptomatic but may present with angina, dyspnea, or syncope. Less frequently, they can cause arrhythmias, valve dysfunction, or emboli. Diagnosis generally requires cardiac MRI or alternate imaging modality. In this report, we present a case of a true atrial septal lipoma with a sessile base protruding into the right atrium discovered during the pedagogic dissection assignment of the interior of the heart. The tumor measured 0.5 × 1.0 cm, and on the cut surface, it appeared yellow and encapsulated. Histopathological examination of the lipomatous mass revealed extensive nodular thickening of the interatrial septum from the accumulation of mature adipose tissue reaching the resection surface. It is possible that the lipoma may have had a space-occupying effect, which would have increased the volume within the right atrium and had an adverse effect on tricuspid valve function. This is consistent with the dilated and thin-walled appearance of the right atrium. This report contributes to the limited literature on this type of benign, primary cardiac tumor and provides a clear illustration and clinical relevance to showcase the pathology and its possible clinical consequences.