Atrial blood cyst in an adult with regurgitation of mitral and tricuspid valves.

Blood cysts of the heart are extremely rare in adults and usually involve valves or the left ventricle. Although two cases of blood cysts in the right atrium in adults have been reported, a cyst combined with a disorder of the valves has never been reported. We report a 52-year-old woman with a blood cyst that generated from the right atrial septum. Furthermore, the patient had regurgitation of both the mitral and tricuspid valves and then underwent surgical excision of the blood cyst, mitral valve plasty and tricuspid valve annuloplasty. We believe that it is possible to diagnose blood cysts with echocardiography, CT and magnetic resonance imaging. Echocardiography showed the cyst as a circle without a complete inner free-echo. CT and magnetic resonance imaging showed a mass with a non-enhanced inner structure. Furthermore, the latter showed a cyst that was enhanced by T1- but not T2-weighted images, indicating that the content of the cyst was a persistent substance such as blood. Concerning the generation of blood cysts, we hypothesize that heteroplastic growth arising from primitive pericardial mesothelium causes disorders of valves and blood cysts.