Thoracoscopic resection of mediastinal tumor in a patient with azygos continuation of the inferior vena cava.

A 68-year-old man was referred to our hospital because of mediastinal tumor on chest computed tomography (CT). Contrast-enhanced CT showed azygos continuation of the inferior vena cava (IVC). The retro-hepatic IVC was absent superior to the renal veins. The IVC continued into the dilated azygos vein, which joined the superior vena cava. The hepatic vein drained directly into the right atrium. The mediastinal tumor was close to the dilated azygos vein. Video-assisted thoracoscopic resection of the mediastinal tumor was performed, using four ports and CO2 insufflation. Histological examination of the resected specimen revealed a pericardial cyst without malignancy. After a favorable postoperative course, the patient was discharged 4 days after surgery. It is important to recognize this anomaly before thoracic surgery, because transection of the azygos vein can be fatal. Video-assisted thoracoscopic resection of mediastinal tumor close to the azygos vein using CO2 insufflation avoids injury to the azygos vein.