Primary Cardiac Diffuse Large B-Cell Lymphoma: A Diagnostic Pitfall With Overlapping Imaging Features

Primary cardiac lymphoma (PCL) is an exceptionally rare cardiac malignancy with heterogeneous presentations and variable multimodality imaging features.

A 60-year-old man presented with heart failure and complete atrioventricular block. Echocardiography revealed a massive infiltrative right atrial mass with pericardial effusion. The mass demonstrated malignant features on cross-sectional imaging. As biopsy was considered high risk and a definitive pathologic diagnosis was lacking, radiotherapy was initiated in the setting of a structural oncologic emergency to maintain clinical stability, and extracardiac biopsy ultimately established primary cardiac diffuse large B-cell lymphoma. The patient received dose-adjusted R-EPOCH chemotherapy, achieving complete metabolic response after 3 cycles.

PCL and cardiac angiosarcoma can share overlapping imaging features that may delay diagnosis; early histopathological confirmation is pivotal to guide therapy. In selected cases, radiotherapy can provide temporary stabilization until tissue diagnosis is established.

PCL requires individualized management in the absence of established guidelines.