Thoracoscopic approach to the resection of idiopathic azygos vein aneurysm: a case report.

<bold>Background: </bold>Azygos vein aneurysm (AVA) is a rare thoracic pathological entity that mimics a posterior mediastinal mass. However, the pathogenesis of primary azygos vein aneurysms is not clear and its pathology is still being discussed. Some of the AVA are asymptomatic and usually discovered accidentally by routine physical examination.<bold>Case Presentation: </bold>We report the case of a 37-year-old woman who had an azygos vein arch aneurysm with no obvious clinical symptoms. With the analysis of clinical features of the case and AVA morphological characteristics, the AVA was found by a chest computed tomography. Then, enhanced chest computed tomography showed a soft-tissue mass (4.9 × 3.7 × 3.2 cm) in the right posterior mediastinum, which was connected to the superior vena cava and significantly enhanced with contrast agent stratification. The density of the tumor in the delayed stage was the same as that in the azygos vein. The patient underwent video-assisted thoracoscopic surgery. Histopathological evaluation of the surgical biopsy specimen proved to be a completely thrombosed aneurism of the azygos vein arch.<bold>Conclusions: </bold>AVA is a rare pathology that must be taken into consideration during the differential diagnosis of right posterior mediastinal masses. Thoracoscopic surgery is one of the most preferred treatment options for azygos vein aneurysm. [ABSTRACT FROM AUTHOR]