Case 59

Pericardial Lipoma

Clinical Features

Cardiac lipoma most commonly occurs in the right atrium. It is the second most common benign primary cardiac neoplasm following myxoma. Other locations include the epicardium, endocardium, interatrial septum, and left ventricle. Pericardial lipomas are less common, but they are among the more common masses of the pericardium. Lipomas tend to be soft and flexible, and even large tumors may not compress the heart. They are usually asymptomatic. If there are symptoms of compression, such as pain or shortness of breath, then surgical resection is usually performed.

CT and MRI Features

On CT scan, a pericardial lipoma manifests as a homogeneous, low-density mass (negative Hounsfield units) in the pericardium that is relatively pliable without much mass effect (Figure). There is generally no enhancement and no signs of invasion. Fat saturation MRI sequences are ideal for demonstrating that the mass is composed of fat.

Associations

Multiple fat-containing masses within the myocardium have been described in patients with tuberous sclerosis. Current pathologic literature suggests these fatty lesions may simply represent unencapsulated fat cells rather than true encapsulated cardiac lipomas.