Accessory tricuspid valve leaflet in an asymptomatic adult.

A 60-year-old, asymptomatic woman with no relevant cardiac history underwent 2-dimensional transthoracic echocardiography as part of a study protocol. The echocardiogram (Fig. 1) indicated the presence of a large mobile mass on the anterior leaflet of the tricuspid valve without notable regurgitation or obstruction. Electrocardiographic, chest radiographic, and laboratory values were within normal ranges. Cardiac magnetic resonance imaging (MRI) (Fig. 2) revealed a markedly redundant, elongated tricuspid valve leaflet that prolapsed into the right atrium. Cardiac MRI also showed a separate, parachute-like daughter structure attached to the anterior papillary muscle by chordae tendineae (Fig. 2, arrow). The presence of a tricuspid valve mass could not be excluded, and cardiac surgery was deemed necessary due to the large size and mobility of the tricuspid mass and the risk of subsequent obstruction or embolization. Surgery revealed redundant, myxomatous tricuspid valve tissue that was adherent to the anterior and septal leaflets, giving the appearance of a tricuspid valve tumor. A secondary parachute-like structure was also seen. The abnormal tissues were excised by careful dissection. A Carpentier-Edwards ring was implanted, and suture valvuloplasty of the remaining valve leaflets was performed. Histopathologic analysis showed markedly thickened and distorted leaflet architecture with fibrotic, myxomatous, and stromal degeneration of the middle spongiosa layer, which confirmed the diagnosis of accessory tricuspid valve leaflet (Fig. 3).