A large pericardial cyst compressing the left atrium presenting as a pericardiopleural efussion.

Pericardial cysts are rare congenital abnormalities with a reported incidence rate of 1:100,000, accounting for about 7.6% of all mediastinal masses. These cysts frequently occur in the right cardiophrenic angle and their diagnosis is usually suspected after an abnormal chest X-ray is obtained. Herein, we present a case of pericardial cyst compressing the left atrium complicated by a pericardial effusion and pleural effusion in a 62 year-old man with chest discomfort and dyspnoea. After the pericardial cyst was surgically removed, the histopathological examination revealed an inflamed pericardial cyst lined with mesothelial cells.