[Posterior Mediastinal Cyst Resection during Cardiac Surgery through Median Sternotomy:Report of a Case].

A 47-year-old man presented with hematuria. Computed tomography( CT) showed a posterior mediastinal cyst. Chest magnetic resonance imaging showed a well defined mass with high intensity on T2-weighted images. Echocardiogram revealed severe aortic regurgitation, moderate mitral regurgitation and no continuity between the cyst and the pericardium. We performed aortic valve replacement, mitral annuloplasty and cyst resection after confirming it was not malignant by intraoperative rapid pathological examination. We performed sufficient and safe cyst resection through full sternotomy under cardiac arrest. Pathological examination revealed that cyst was bronchogenic. Bronchogenic cyst has malignant potential and it is very difficult to resect after presenting symptoms. We need to consider the differential diagnosis, the timing of operation and operative strategy.