A patient was admitted to our institution with a diagnosis of a cardiac tumor, most likely myxoma, in the right atrium, detected at echocardiography. The cardio-magnetic resonance examination was performed and depicts a homogeneous fatty content, fatty proliferation and hypertrophy along the wall of the right atrium and the interatrial septum, sparing the oval fossa and mimicking a tumor with a filling defect and with slight compression of the inferior and superior vena cava. With the help of double and triple inversion techniques, magnetic resonance imaging can give a tissue-specific diagnosis, in this case a fat-equivalent lesion of the type of lipoma or lipomatous hypertrophy, and thus save additional studies and predetermine the therapeutic approach.