Fig. 1

a. Dilated jugular veins and collaterals in the upper body. b. Transthoracic echocardiogram, subcostal view showing a large mass infiltrating the interatrial septum and extending mainly in the right atrium. c. Transesophageal echocardiogram, bicaval view showing a heterogeneous mass infiltrating the interatrial septum, filling almost three quarters of the right atrium, occluding the superior vena cava at its junction with the right atrium and extending into the left atrium. d. Cine MRI demonstrates a large infiltrating mass extending in both atria, occupying most of the right atrium, involving the surrounding pericardium leading to a mild pericardial effusion, and causing a grade of ostial stenosis of the lower right pulmonary vein. e. Cine MRI right ventricular long axis view with extension of neoplasm to the atriocaval junction and superior vena cava. f. Contrast-enhanced CT scan demonstrates a dilated azygos vein (arrow). g. 18-FDG PET/CT sagittal views showing increased 18-FDG-uptake within the tumor in the right atrium and h. complete tumor remission. i. Cine MRI four-chamber axial view showing no evidence of the tumor