Lipomatous hypertrophy of interatrial septum (LHIS), usually found in echocardiography, is a rare non-neoplastic disease entity, which may cause arrhythmia or sudden death. We reported a case of LHIS associated with hypertrophic cardiomyopathy (HCM), which was suspected a hyperechoic intraatrial tumor in transthoracic echocardiography. Magnetic resonance (MR) imaging showed fat infiltration of ...