Ectopic congenital thymic cyst in the right pleural cavity.

A 37-year-old man with a huge pleural cyst, presented with symptoms of right heart compression. The mass on the right side of the chest seemed initially to be in connection with the mediastinum. Computed tomography failed to define its relationship with the pericardium, and echocardiography excluded any involvement of the mediastinal structures. The final diagnosis was a congenital thymic cyst exclusively located in the pleural cavity.