(157) Under Pressure: Identifying "Idiopathic" Causes of Pericardial Effusions

Introduction: Approximately a third of pericardial effusions are classified as idiopathic. When initial testing does not yield an etiology, consider further evaluation for systemic inflammatory or neoplastic conditions.

Description: An 82-year-old woman with hypertension and hyperlipidemia presented with a 3-month history of progressive dyspnea.
The initial workup was notable for a chest radiograph showing cardiomegaly with tracheal deviation. A bedside ultrasound demonstrated a pericardial effusion with right ventricular diastolic collapse concerning for tamponade physiology. Subsequently, an emergent pericardiocentesis yielded 1.1 liters of serous fluid without signs of infection or malignant cells. Further testing showed a large anterior epicardial fat pad; evaluation for TTR amyloid, monoclonal gammopathy, and autoimmune conditions was unremarkable. Therefore, the pericardial effusion was labeled idiopathic.
Two weeks later, she returned with generalized weakness and dysarthria. A neurologic exam was significant for right hemibody ataxia, restricted extraocular movements, and generalized hyperreflexia. Head imaging revealed bilateral enhancing retro-orbital masses, a right intracranial lesion with mass effect on the medulla and cerebellum, and encasement of surrounding neurovasculature. She was admitted to the ICU for further evaluation.
Subsequent imaging demonstrated diffuse pericardial thickening, a bone scan showed widespread increased uptake consistent with an infiltrative process, and a biopsy of the right tibia revealed nonspecific fibrohistiocytic infiltrate. A PET-CT confirmed previous findings with extensive involvement of bones, brain, pericardium, adrenals, and kidneys. Genetic testing was positive for a BRAF V600E mutation consistent with Erdheim-Chester Disease.
The patient was started on vemurafenib and follow-up revealed a significant decrease in disease activity.

Discussion: Pericardial effusion may be an early manifestation of a systemic condition. Erdheim-Chester Disease is a multisystem disorder of non-Langerhans histiocytes that often presents with osteosclerosis, cardiovascular infiltration, and central nervous system involvement. It is important to remember Erdheim-Chester Disease as a potential diagnosis for pericardial effusions as it can lead to more effective treatment.