Blood cyst of the pulmonary valve in an adult: report of a case and review of the literature.

We report a case of a blood cyst originating from the pulmonary valve cusp of a 43-year-old Japanese woman with pulmonary stenosis. Cineangiography revealed a pedunculated tumor on the arterial surface of the pulmonary valve. It was successfully removed by a transpulmonary artery approach. The cyst contained old blood and calcified thrombi, and its wall consisted of collagenous fibrous tissue. Immunohistochemically, a monolayer of flat cells lining the cyst was confirmed as endothelium using antibodies to von Willebrand factor and CD34, as well as UEA-I lectin. To the best of our knowledge, blood cysts of the pulmonary valve are rare and only 10 such cases have been reported, including six pediatric cases. This case is the oldest and fifth adult patient with a blood cyst found on the pulmonary valve. A possible histogenesis is discussed.