Entodermal inclusion cyst of the tricuspid valve.

This is a report on an epithelial inclusion cyst covering the septal leaflet of the tricuspid valve. The tumor was an accidental finding in a 5 1/2 years-old boy with congenital heart disease including double-chambered right ventricle, ventricular and atrial septal defects and subvalvular aortic stenosis. Histological examination showed a two-layered ciliated epithelium, typically present in the respiratory system. Embryologic tissue heterotopia arising from sequestered entodermal elements from the primitive foregut during cardiac organogenesis is a possible explanation for the locality and histology of the tumor. To our knowledge, a similar case has never been presented before.