Multimodality Imaging of an Unusual Case of Right Ventricular Lipoma
A 57-year-old man presented with mild dyspnea and fatigue on exertion. He had a history of hypertension and type 2 diabetes mellitus. The results of the physical examination were normal, with the exception of a grade II ejection systolic murmur over the aortic area. ECG showed normal sinus rhythm. An echocardiogram was performed for evaluation of cardiac murmur.
Transthoracic echocardiogram showed a bicuspid aortic valve, with mild aortic stenosis (peak gradient, 16 mm Hg), but no regurgitation. Cardiac function was normal. Incidentally, an echogenic mass measuring 4.0×2.5 cm was seen adherent to the right ventricular (RV) free wall and RV outflow tract (Figure 1 and Movie I in the online-only Data Supplement).
To further characterize the mass, the patient underwent cardiovascular MRI. Cine steady-state free precession imaging demonstrated normal ventricles and low normal left ventricle systolic function. A well-defined, lobulated mass was seen in the anterosuperior aspect of the RV free wall, extending to the RV outflow tract. The mass had an intermediate signal in steady-state free precession images and a high signal in T1- and T2-weighted images, and it showed signal dropout with fat saturation sequences (Figure 2A and 2B and Movie II in the online-only Data Supplement). There was no evidence of pericardial invasion. First-pass perfusion imaging showed no perfusion in the mass (Figure 2C). Regional wall motion near the mass was normal. Based on these imaging characteristics, a diagnosis of cardiac lipoma involving the RV outflow tract was made, and the patient was scheduled for follow-up imaging.
A follow-up echocardiogram performed 3 months later showed a mild increase in the size of the mass, as a result of which surgery was planned. Preoperative cardiac catheterization showed mild to moderate stenosis of the left anterior descending artery, but did not show any compression of the right coronary artery by the RV mass. Operative findings showed a large, lobulated fatty mass in the RV free wall that protruded into the cavity and infiltrated the myocardium, but the acute margin of the RV and the pulmonic valve were spared. Surgical resection with patch reconstruction was performed. Histopathology showed a benign encapsulated lipoma composed of mature adipocytes with entrapped cardiac myocytes (Figure 3).
Cardiac lipoma is a rare neoplasm composed of encapsulated mature adult adipose tissue, and is less common than myxoma. It can be seen at any age, with no particular sex predilection.1 It can be intracavitary, intramyocardial, or epicardial. Lipoma in the right ventricular outflow tract has only rarely been reported.2 Cardiac lipoma is usually asymptomatic and often discovered incidentally. However, lipoma can produce obstruction or compression depending on its location. Valvular dysfunction, congestive cardiac failure, and dyspnea due to lung displacement can be seen. Cardiac arrhythmia and peripheral embolization rarely have been reported.3 Echocardiographic appearance depends on the location.1 MRI shows a mass with homogeneous signal characteristics of fat in all sequences.1 Resection or enucleation of the lesion is performed in symptomatic lipomas or when there is suspicion for malignancy. Long-term prognosis is good, in general, but fatal complications have been reported.4
The online-only Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIRCULATIONAHA.111.030213/-/DC1.
- © 2011 American Heart Association, Inc.
- Araoz PA,
- Mulvagh SL,
- Tazelaar HD,
- Julsrud PR,
- Breen JF
- Argiris K,
- Swamy G,
- Tat K