Diffuse Large B Cell Lymphoma Presenting as a Cardiac Mass Complicated by Atrial Arrhythmia.

Cardiac involvement in diffuse large B-cell lymphoma (DLBCL) is uncommon and often presents with nonspecific symptoms, such as chest pain and dyspnea, which can lead to challenges in diagnosis. Cardiac lymphomas most often arise in the right atrium or the pericardium, and can thus result in tachyarrhythmias, pericardial effusions, and heart failure symptoms, all of which can further complicate clinical management. Diagnosis typically requires comprehensive imaging such as cardiac magnetic resonance imaging (MRI) or positron emission tomography-computed tomography (PET-CT), as transthoracic echocardiography (TTE) alone is limited in the diagnosis of intracardiac masses, as well as tissue biopsy for histopathological confirmation. Treatment typically involves systemic chemotherapy, though outcomes are generally poor, as cardiac involvement is generally a late manifestation of DLBCL. This case underscores the importance of early recognition, need for comprehensive imaging and tissue diagnosis, and multidisciplinary care in managing cardiac lymphoma, as well as the challenges associated with refractory disease.