(217) Pausing for Concern: Lymphoma's Arrhythmic Disguise

Introduction: Diffuse large B-cell lymphoma (DLBCL) with secondary involvement of the heart occurs mostly in advanced disease and rarely presents as intracardiac mass. We present a case of relapsed DLBCL who presented with an atrial arrythmia and large atrial mass that was successfully treated with systemic chemotherapy.

Description: A 70-year-old male with a history of stage IV DLBCL in remission for 2 years presented with fatigue and loss of appetite during the surveillance period. On admission, he was hemodynamically stable and saturating 100% on room air. Physical exam was notable for a systolic decrescendo murmur in the mitral area and bilateral lower extremity edema. Laboratory workup revealed hypercalcemia of 13.2 mg/dL and hyperuricemia of 8.5 mg/dL. On Day 1, he developed asymptomatic atrial flutter with an 8.2-second conversion pause on telemetry. Transthoracic echocardiogram (TTE) revealed a new large right atrial mass (3.9 x 3 cm) originating from the lateral wall near the superior vena cava, with normal left ventricular function and wall motion. The patient was started on an amiodarone infusion for rhythm control. Interventional Radiology deferred biopsy of the atrial mass, and the patient was deemed not a suitable surgical candidate. CT scan showed liver lesions and PET scan demonstrated FDG avidity in both the liver and atrium. Biopsy of a liver lesion confirmed DLBCL. The patient was started on R-DHAX (Rituximab, Dexamethasone, Cytarabine, and Oxaliplatin) chemotherapy regimen with a good response. The atrial fibrillation resolved on day 6 with decrease in the size of the atrial mass on repeat TTE. The patient was discharged to a subacute rehabilitation facility with the atrial mass no longer visualized on a follow-up TTE on Day 30.

Discussion: In our patient, the presentation of atrial arrhythmia and finding of a large atrial mass on TTE is a rare occurrence in patients with relapsed DLBCL. Early diagnosis and chemotherapy initiation is necessary to improve cardiac symptoms and reduction of the cardiac mass. Understanding both the potential for cardiac involvement in DLBCL patients and the efficacy of systemic chemotherapy is crucial to improve clinical outcomes.