A 52-year-old homosexual male presented with a 5-month history of anorexia and malaise, a 2-week history of night sweats, pleuritic chest pain, and worsening dyspnea on exertion. A transthoracic echocardiogram to evaluate the cause of his dyspnea revealed significant pericardial effusion with evidence of tamponade physiology, bulky mass (arrowheads) within the coronary sinus (parasternal long axis, Figure 1A, Movie I), and multiple large masses in the right atrium traversing the septum into the left atrium (subcostal, Figure 1B, Movie II). The left ventricular ejection fraction was estimated to be 50%. His blood count showed 5.2×103 white cells/cm3, 39.2% hematocrit, and 279×103 platelets …