Pericardial involvement as a rare manifestation of hypereosinophilic syndrome.

A 56-year-old female with idiopathic hypereosinophilic syndrome who presented with chest tightness, dyspnea and new-onset atrial fibrillation is reported. Work up revealed significant peripheral eosinophilia, pericarditis, and a pericardial effusion with tamponade physiology. Pericardiocentesis revealed predominant eosinophils (88%) in the pericardial fluid.