[Mediastinoscopic diagnosis and drainage of pericardial diverticulum--a case report].

A 38-year-old male was suspected of having an enlarged pretracheal lymph node on chest CT scan. At mediastinoscopy, a cystic lesion was recognized, and showed repeated dilatation and contraction synchronously with the cardiac beat. Pneumopericardium was demonstrated by intraoperative pneumocystography. The cystic lesion was diagnosed as pericardial diverticulum. The diverticular wall was partially resected for drainage of the pericardial fluid. Mediastinoscopy as a less invasive procedure may be useful for the differential diagnosis of adenopathies, and in case of lesion such as a small pericardial diverticulum may allow treatment.