Giant epicardial cyst presenting as acute cardiac tamponade in a 2-year-old boy.

Cystic structures within the pericardial cavity are rare. They are divided into epicardial and pericardial variants. Pericardial and epicardial cysts rarely cause symptoms. This report describes a case of epicardial cyst with acute cardiac tamponade in a 2-year-old boy with no previous cardiac history who was transferred to our hospital because of hemodynamic instability. Emergency drainage of the pericardial effusion and complete excision of the cyst were performed through a median full sternotomy.