Case Presentation: A 59 year-old male with a past medical history of Type 1 muscular dystrophy presented to the emergency room with acute onset of chest pain. The patient reported he had some mild abdominal and epigastric pain the night prior, but in the morning, it became intolerable chest pain. The pain was described as sharp, pleuritic in nature, 10/10 over the left side of his chest. On admission, the patient’s vital signs were as follows: blood pressure 113/68, heart rate 72, respiratory rate 18, oxygen saturation of 95% and temperature 98.7F. His physical exam was significant for rhonchi in the left lower lobe, and upper and lower extremity weakness, with distal weakness greater than proximal. The EKG showed sinus rhythm with an incomplete right bundle branch block, which is also noted in an EKG 8 years prior. Troponin T was less than 0.01 on two separate measurements, taken six hours apart. Creatinine kinase measured 30 and CKMB was 1.0. The chest x-ray revealed a left lower lobe opacity. Given an unrevealing EKG and negative cardiac enzymes, acute coronary syndrome was lower on the differential diagnosis, and patient underwent a CT angiogram of the chest. The CT showed fat stranding in the pericardial space concerning for epipericardial fat necrosis, and a small left sided pleural effusion; no pulmonary emboli were identified. The cardiothoracic surgery team was consulted for further evaluation of the fat necrosis, who advised to treat conservatively with NSAIDs. The patient’s pain markedly improved on hospital day two and by hospital day three, it had resolved. His hospital course was further complicated by aspiration pneumonia with development of a loculated pleural effusion requiring a video assisted thoracoscopy.
A repeat CT scan of the chest performed four weeks later, demonstrated resolution of the pericardial fat necrosis.

Discussion: Epi-pericardial fat necrosis (EPFN) is a rare condition that causes acute onset chest pain. EFPN is an inflammatory disorder where patients present with pleuritic chest pain, which may last from hours to days. It can often be mistaken as a life-threatening disorder such as pulmonary embolism, pericarditis or myocardial infarction. Chest x-rays can be clear or may demonstrate an opacity at the cardio-phrenic angle. A chest CT is the imaging modality of choice, which usually reveals a mass with fat attenuation, often encapsulated, adjacent to the pericardium with surrounding inflammatory changes. A pleural effusion can also be seen in addition to the fat necrosis. The pathophysiology is poorly understood, although it has been hypothesized it may be secondary to vascular pedicle torsion or pre-existing structural abnormalities. In the past, the diagnosis of EPFN required tissue diagnosis, but recent literature suggests a CT is sufficient to make the diagnosis.

Although EPFN is an uncommon disease, it is especially relevant in the hospital setting where patients often present with acute chest pain. The treatment of EPFN is frequently conservative and targeted towards pain control with NSAIDs. Resolution can be determined with a follow up CT scan few weeks after the episode.

Conclusions: Epipericardial fat necrosis in an uncommon cause of chest pain. It often presents as acute onset pleuritic chest pain, and should be included on the differential diagnosis of acute chest pain in patients who have been ruled out for life-threatening etiologies such as myocardial infarction or pulmonary embolism.