Superior vena cava syndrome from an invasive thymoma with transcaval invasion to the right atrium

Invasive thymoma with transcaval extension to the right atrium is a rare cause of superior vena cava syndrome. We present a case on a 74-year-old female presenting with dyspnea on exertion, and facial and upper extremity swelling. Physical examination revealed mild facial swelling, non-pitting edema involving the upper extremities and distention of superficial veins of the anterior chest wall and jugular veins. An echocardiogram showed moderate right atrial dilation with a mobile mass in the atrial cavity prolapsing through the tricuspid valve. Cardiac magnetic resonance imaging revealed a 9.9 × 4.3 cm heterogeneous mass in the anterior mediastinum compressing the superior vena cava and endovenously extending into the right atrium. Tissue biopsy of the mediastinal mass revealed a type B1 thymoma, further staged as a Masaoka IVa invasive thymoma that underwent successful en bloc resection followed by removal of intracaval and right atrial mass.