Imaging description

On CT, epipericardial fat necrosis appears as an encapsulated area of fat with surrounding inflammatory changes in the cardiophrenic region. The encapsulated fat has a high attenuation, thickened rim with adjacent fat stranding and possible thickening of the adjacent pericardium (Figure 13.1). The surrounding capsule demonstrates enhancement after the administration of IV contrast. Multiplanar reconstructions help exclude any communication with abdominal fat due to diaphragmatic defects (Figure 13.2). The name epipericardial fat necrosis is currently preferred over pericardial fat necrosis, a term used in the past to describe this entity, given that the involved fat is located in the cardiophrenic space outside of the pericardium. Conservative treatment with anti-inflammatory medications and analgesics demonstrate resolution of these findings on imaging.

Importance

Epipericardial fat necrosis is an uncommon benign condition presenting with acute pleuritic chest pain. Possible etiologies include acute fat torsion or hemorrhagic necrosis from increased thoracic pressure after Valsalva maneuver resulting in increased capillary pressure. Pathologic features are similar to fat necrosis in other locations such as the omentum, breast, and epiploic appendagitis. Although uncommon, this entity can be easily diagnosed on CT or MRI due to its characteristic imaging findings. A correct diagnosis by the radiologist can avoid patients the risk of unnecessary invasive testing to exclude coronary artery disease such as catheter angiography.

Typical clinical scenario

Epipericardial fat necrosis may be identified on chest CT performed for the evaluation of acute onset pleuritic chest pain. Imaging follow-up after conservative management demonstrates complete resolution of the CT findings and is sufficient to confirm the diagnosis.

Differential diagnosis

Diaphragmatic hernias through a diaphragmatic defect can be excluded using multiplanar reconstructions on CT. Lipoma usually does not have surrounding fat stranding. Malignant lesions such as liposarcoma, teratomas, and thymolipomas have a more aggressive appearance with presence of soft tissue components. Infectious conditions such as mediastinal abscess are accompanied by a fluid collection.