[Surgery for a pericardial diverticulum; report of a case].

We report a case with pericardial diverticulum in the mediastinum. A 64-year-old woman visited our hospital because of cough and dyspnea. Chest X-ray showed a smooth-bordered mass in the right superior mediastinum and computed tomography (CT) showed a homogeneous cystic mass in the paratracheal area. During right mini-thoracotomy, a thin-walled cystic lesion was found involving the trachea, the superior vena cava, and the azygos vein. The cyst extended a duct toward the pericardium. We performed total excision and pathological examination confirmed the diagnosis of a pericardial diverticulum. Mini-thoracotomy provides an effective and minimally invasive means of excising the mediastinal mass, relieving symptoms, and allowing pathological examination.