“Tumor and Tamponade” Large Mediastinal Lymphoma Masquerading as Cardiac Tamponade on Transthoracic Echocardiogram

Though malignancy remains the most common cause of cardiac tamponade, large mediastinal T cell lymphoma mimicking as tamponade on transthoracic echocardiogram is rare. In this case report, we describe a 21-year-old otherwise healthy university student with a brief history of dyspnea and flu like constitutional symptoms. He was found to have left sided pleural effusion with pneumothorax on chest radiography with pulsus paradoxus on physical examination. An electrocardiogram also demonstrated low voltage. Chest tube placement and fluid analysis revealed exudate per Lyte's criteria and chest computed tomography revealed a large anterior mediastinal mass with small to moderate pericardial effusion. Transthoracic echocardiogram revealed moderate pericardial effusion and tamponade physiology with right atrial and right ventricular collapse during both systole and diastole. Pericardiocentesis was deferred, as RV diastolic collapse was secondary to large anterior mediastinal mass as opposed to significant pericardial effusion. The patient was started on fractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone chemotherapy regimen as well as intrathecal methotrexate followed 14 days later by repeat transthoracic echocardiogram. This demonstrated resolution of his pericardial effusion, reduction in mass compression, and proper right ventricular filling.