[Unusual cyanosing heart defect due to supravalvular tricuspid obstruction in an infant].

We present a case involving a rare form of cyanotic congenital heart disease in a 2-month-old neonate. The initial diagnosis was thought to be tricuspid dysplasia with right-to-left shunting through an interatrial communication. However, surgery showed the presence of a pedunculated mass that prolapsed into the tricuspid valve orifice, thereby causing severe obstruction to right ventricular filling. This mass was attached to the lower part of the atrial septum. Pathological examination showed fibrotic myxoid tissue. After the mass was resected surgically, the tricuspid valve appeared normal. We comment on the pathogenesis and the differential diagnosis of this rare entity.