Giant Left Atrial Appendage Aneurysm Mimicking Mediastinal Mass and Associated with Incessant Atrial Arrhythmias.

Left atrial appendage aneurysm (LAAA) is a rare entity. Clinical manifestations include arrhythmias and systemic embolization. We show here an example of a large and ectopic LAAA mimicking a mediastinal mass on chest X-ray and presenting with incessant atrial arrhythmias. Subsequent investigations leading to the correct diagnosis are described.