Segmental Agenesis of the Azygos Vein: A Case Report and Literature Review

This is the authors' abstract. We don't add key points for this paper.

Congenital anomalies of the azygos venous system are uncommon and usually asymptomatic. This report describes a segmental agenesis of the superior azygos vein associated with an empty azygos fissure. We present the case of a 60-year-old woman with a suspected pulmonary mass on chest radiography. Contrast-enhanced thoracic computed tomography (CT) demonstrated an azygos fissure devoid of its usual vascular content. The normal azygos arch was absent above the level of T7–T8. A venous channel was identified along the left posterolateral aspect of the descending thoracic aorta, continuing superiorly above the aortic arch and draining into the left brachiocephalic vein. The inferior azygos segment appeared to communicate with the left-sided venous pathway around T7–T8, suggesting drainage through the hemiazygos and accessory hemiazygos system and the left superior intercostal vein. The coexistence of an empty azygos fissure and a suspected segmental agenesis of the superior azygos vein represents an unusual venous configuration that may reflect a complex developmental anomaly of the azygos system.