LAUSR

Hepatic and renal cysts are relatively common among healthy people, but there are few published reports of primary cysts of the atrial septum. Here, we report a case of an unusual cyst of the atrial septum accompanied by atrial septal defect (ASD) in a 42‐year‐old woman. Microscopic examination showed the deposition of calcium salts within the tissue mass and an organized thrombus surrounded by a fibrous capsule. The case was discussed with reference to the relevant published literature and compared to other documented types of atrial septal cysts. The final diagnostic conclusion was a primary atrial septal cyst.