Right- and left-sided interatrial septal aneurysm mimicking atrial tumor and stroke.

We report the cases of two patients with cerebral embolization and interatrial septal aneurysm. Transesophageal echocardiography required for stroke showed right-sided interatrial septal aneurysm in the first patient and left-sided interatrial septal aneurysm in the second. In the two patients, interatrial septal aneurysm was mimicking atrial cystic tumor or abscess. Significant internal carotid artery stenosis was found in the first patient and aortic arch atheroma with mobile components but no patent foramen ovale in the second patient. In the two patients, interatrial septal aneurysm appears to be only an incidental finding and not the true cause of stroke. Furthermore, we discuss the differential diagnoses of atrial masses.