Right atrial thrombus masquerading as intracardiac cyst: a case report.

Intracardiac cystic lesions are rare. Hydatid disease, blood cysts and bronchogenic cysts in various chambers of the heart have been reported. Right atrial thrombus presenting as a cystic lesion on echocardiogram has not been reported. We describe a patient with mitral regurgitation in atrial fibrillation with a right atrial cyst, which was found to be a cavitating thrombus.