From hypertrophic phenotype to ventricular tachycardia and ICD implantation: cardiac involvement by diffuse large B‑cell lymphoma mimicking hypertrophic cardiomyopathy: a rare case report

Background Cardiac involvement by diffuse large B‑cell lymphoma (DLBCL) is rare and frequently presents with non‑specific cardiac findings. Diffuse myocardial infiltration may resemble hypertrophic cardiomyopathy (HCM), leading to delayed diagnosis and treatment. Case presentation A 57-year-old man presented with postprandial left upper abdominal discomfort and a low-grade fever. Endoscopic ultrasound-guided pancreatic biopsy established non-Hodgkin lymphoma, consistent with DLBCL of the germinal-center B-cell (GCB) subtype. Retrospective review revealed a history of unexplained pericardial effusion, progressive electrocardiographic changes, and progressive ventricular wall thickening that had been diagnosed as HCM. At admission, cardiac troponin I (cTnI) was markedly elevated. Echocardiography showed diffuse hypoechoic thickening of both ventricles, a right atrioventricular-groove mass, reduced left ventricular ejection fraction (LVEF), and severe impairment of global longitudinal strain (average GLS − 2.8%). ¹⁸F‑FDG PET/CT demonstrated intense uptake in the pancreas and myocardium. Cardiac magnetic resonance (CMR) strongly suggested extensive myocardial infiltration. After eight cycles of R‑COEP chemotherapy, multimodality imaging suggested the resolution of the pancreatic lesion and partial regression of myocardial involvement. Subsequently, a single cycle of bridging chemotherapy with gemcitabine and oxaliplatin was administered, followed by three cycles of Pola‑R‑GEMOX and one year of lenalidomide maintenance therapy, which resulted in regression of the myocardial lesions and normalization of cardiac biomarkers. However, apical fibrosis and left ventricular systolic dysfunction persisted. Three years after the index admission, the patient experienced two episodes of asymptomatic self-terminating ventricular tachycardia (VT) of undocumented duration and underwent implantable cardioverter-defibrillator (ICD) implantation. Conclusions Lymphomatous cardiac infiltration should be considered in patients with unexplained progressive myocardial thickening, especially when accompanied by pericardial effusion, biomarker elevation, and electrocardiographic abnormalities. Multimodality imaging can identify an infiltrative phenotype, guide biopsy, and monitor treatment response. Persistent myocardial fibrosis may confer long‑term arrhythmic risk despite substantial tumor regression.