Cardiac lipomas are benign tumors and account for a small number of the primary tumors of the heart [
2]. They can occur in any age group, but are most prevalent between ages 40–60 years [
3]. They are usually asymptomatic and hence remain undetected or are discovered incidentally. Symptoms, when present, are varied and depend on the location of the heart involved. Tumors in the subepicardial region can create a mass effect on nearby structures. They can cause angina if they compress the coronary arteries or they can reduce systolic function by compressing on the left ventricle. Tumors in the myocardium can infiltrate the electrical circuit and be a nidus for arrhythmogenesis. That being said, the most common location is the subendocardial region, with a particular predilection for the right atrium and the left ventricle. Depending on the chamber involved and the size of the mass, they can cause obstruction of flow and congestive heart failure [
4,
5]. Embolization is a rare phenomenon because lipomas are typically encapsulated.
Diagnostic evaluation begins with an echocardiogram that offers a simple and non-invasive approach. However, it may not be able to visualize smaller tumors. Furthermore, echocardiography often cannot conclusively differentiate between lipomas and other primary tumors of the heart [
6]. In such situations, computerized axial tomography and magnetic resonance imaging may be of additional value. While lipomas appear to not enhance and have homogenous high signal intensity on T1 and T2 weighted images, liposarcomas typically contain solid, enhancing components intermixed with areas of fat signal [
1]. Another differential diagnosis for a fat containing mass within the heart is lipomatous hypertrophy of the interatrial septum. In reality, lipomatous hypertrophy is a misnomer as the pathophysiology involves hyperplasia of adipocytes as opposed to hypertrophy. Unlike lipomas, these are unencapsulated, spare the fossa ovalis and thus bear a dumbbell shape [
6]. In our case, although the MRI findings were nearly conclusive for lipoma based on tissue characteristics, the multiple septations, extensive involvement of the right atrium and interatrial septum, as well as the inferior cavoatrial junction and coronary sinus raised concerns for well-differentiated liposarcoma. Thus, a pre-operative biopsy was performed which confirmed a simple lipoma with no evidence for malignancy. The sample was negative for MDM2 gene amplification which has a 93.5% sensitivity for detecting atypical and malignant lipomatous tumors [
7]. To complete the work-up of a cardiac tumor, a left heart catheterization becomes important to delineate the coronary anatomy, particularly for those who would eventually need surgery. Apart from evaluating for coronary artery disease, the benefit of a catheterization is two-fold. Not only does it provide information on whether the tumor is compromising vascular supply to the myocardium, but it also gives details on the vascular supply to the tumor [
1].
Given their low prevalence, there are no randomized clinical trials to guide treatment. A surgical approach is justified in patients who are symptomatic, to alleviate symptoms and to prevent progression of disease. However, treatment in asymptomatic patients poses a serious dilemma to the patient and the clinician as there is no consensus to date [
4].