Abstract
Right atrial diverticulum is a rare congenital anomaly that is most often detected incidentally on cardiac imaging. We report the case of a 51-year-old patient who underwent coronary computed tomography angiography for exclusion of coronary artery disease, in whom a small saccular outpouching measuring 6 mm was identified arising from the anterolateral wall of the right atrium. The lesion demonstrated a communicating neck and homogeneous contrast opacification identical to the atrial cavity. This characteristic location corresponds embryologically to the incorporation site of the right sinus venosus into the primitive atrium, a region recognized for structural remodeling during cardiac development. Recognition of this entity is essential to differentiate it from atrial appendage variants, aneurysms, or pericardial lesions.