A 60-year-old asymptomatic man was referred for assessment of an intracardiac mass. He had a history of bladder cancer and surgery for subcutaneous lipoma. Computed tomography of the chest performed to evaluate bladder neoplasia extension showed a right atrial mass (6.8 × 3.4 cm; Fig. 1 .1 ). Transoesophageal echocardiogram demonstrated a non-protruding intracardiac mass (5 × 5 cm; Fig. 1 .2) localized within the interatrial septum but without extension to the foramen ovale. There was no sign of right atrial inflow obstruction. The workup was completed with cardiovascular magnetic resonance (CMR), which confirmed the diagnosis of typical lipomatous hypertrophy of the interatrial septum (LHSIA) showing a spontaneous hyper signal on T1- and T2-weighted black-blood spin echo images and no contrast enhancement after gadolinium injection ( Figs. 1 .3 and 1.4). The thickened tissue was extended to the posterior wall of the right atrium with a non-significant compression of the superior vena cava. Our heart team rejected the idea of surgery in this asymptomatic patient with an uncomplicated mass.
