Hypertrophic Cardiomyopathy Mimicking Cardiac Involvement on 18F-FDG PET/CT in a Patient With Lymphoma.

18F‑FDG PET/CT was performed on a 78‑year‑old woman for initial staging of newly biopsy‑proven follicular lymphoma. The scan revealed focal uptake at the left ventricular apex, along with multiple hypermetabolic lymph nodes in the cervicothoracic region. Subsequent cardiac magnetic resonance imaging, performed to exclude cardiac lymphomatous involvement, demonstrated asymmetric hypertrophy of the interventricular septum and apical myocardium, with late gadolinium enhancement in the apex, supporting the diagnosis of hypertrophic cardiomyopathy. Follow‑up 18F‑FDG PET/CT after chemotherapy showed persistent apical uptake, despite metabolic remission of the lymphoma.