Microbubbles contrast inside the cyst: a pathognomonic sign of mitral valve blood cyst.

We report a case of giant blood cyst originating from the anterior mitral valve leaflet in an 18-year-old white girl. Contrast real-time transthoracic echocardiogram showed the presence of microbubbles inside the cystic cavity during diastole, confirming the presence of blood passage between the ventricular cavity and the cyst lumen and suggesting that this is a pathognomonic sign of the presence of a blood cyst. Although, in previous cases, contrast microbubbles inside the cyst have been described during systole, we report the presence of microbubbles during diastole.