Great mimicker: definite isolated cardiac sarcoidosis masquerading as hypertrophic cardiomyopathy.

A healthy man in his 50s was hospitalised after presenting with chest pain and dyspnoea. An echocardiogram revealed asymmetrical septal hypertrophy, leading to a diagnosis of hypertrophic cardiomyopathy. Due to progressive conduction abnormalities during his hospitalisation, further evaluation was performed. Cardiac MRI revealed dense late gadolinium enhancement of the septum in the area of hypertrophy. Additionally, fluorodeoxyglucose-positron emission tomography demonstrated increased uptake within the same region, suggestive of active inflammation. Subsequent endomyocardial biopsy showed non-caseating granulomatous inflammation, consistent with cardiac sarcoidosis. Treatment with prednisone and methotrexate was initiated, and an implantable cardioverter-defibrillator was placed following thorough risk stratification. This case highlights the importance of multimodality imaging and the pursuit of a tissue diagnosis in the evaluation of cardiomyopathy.