Left atrial appendage aneurysm in a child

We report a case of left atrial appendage aneurysm in a 1-year-old child. The patient was asymptomatic, and a mediastinal liquid mass that was confirmed to be an aneurysm of the left atrial appendage was incidentally revealed by transthoracic echocardiography. Aneurysmectomy was performed during cardioplegic arrest under the support of cardiopulmonary bypass. The postoperative course was uneventful.