Fulminant Cardiac Sarcoidosis Resembling Giant Cell Myocarditis: A Case Report

Background Severe cardiac sarcoidosis (CS) can share clinical and histopathologic features with giant cell myocarditis (GCM).Case summary A 56-year-old female presented with 1 week of exertional chest pressure and dyspnoea. Echocardiogram demonstrated extensive regional dysfunction with left ventricular ejection fraction (LVEF) 38%. Cardiac catheterization revealed no obstructive coronary artery disease and cardiac index 1.5 L/min/m(2). Cardiac magnetic resonance imaging (MRI) demonstrated diffuse late gadolinium enhancement. Positron emission tomography with fluorodeoxyglucose (FDG) (FDG-PET) computed tomography showed FDG uptake in the anteroseptal and anterior wall and no extracardiac activity. Endomyocardial biopsy (EMB) demonstrated fragments of endocardial fibrosis with mixed inflammatory infiltrate including histiocytic giant cells, which could be due to CS or GCM. She was initially treated for GCM with high dose steroids, tacrolimus, and mycophenolate mofetil. Repeat EMB was pursued and demonstrated multiple granulomas with sharp demarcation from adjacent uninvolved myocardium consistent with CS. A dual-chamber implantable cardioverterdefibrillator was placed, and immunosuppression was changed to prednisone alone with plan for infliximab.Discussion This case illustrates a rare presentation of fulminant isolated CS. Endomyocardial biopsy with sufficient tissue was critical to establish a diagnosis and initiate appropriate immunosuppression.