Giant left atrium mimicking right pleural effusion

Giant left atrium is a rare condition normally resulting from mitral valve disease, especially Rheumatic heart disease. Several definitions have been presented for giant left atrium, but this condition is usually termed giant left atrium when the left atrial diameter exceeds 80 or and 65 mm. Giant left atrium is the end product of severe and prolonged pressure and volume overload, occurring mainly during mitral insufficiency, stenosis, and rarely in mitral valve prolapse alone4This condition may predispose the patient to atrial arrhythmia, atrial thrombosis and systemic embolization. It may also compress adjacent structures or mimic pleural effusion. It is defined left atria larger than 6 cm in diameter as giant left atrium. In this case report, we present a 75-year-old woman with giant left atrium, which was mistaken for right pleural effusion.