The Azygos Lobe: A Comprehensive Review

Abstract

The azygos lobe, an uncommon anatomical variation in the right lung that was initially described by Heinrich Wrisberg in 1877, presents a unique structural anomaly that challenges both radiological interpretation and surgical intervention. Unlike true accessory lobes, it lacks an independent bronchus and vascular supply, arising instead from an aberrant course of the azygos vein during embryogenesis. This deviation leads to the formation of the azygos fissure, a distinctive pleural separation composed of four layers. While typically asymptomatic, the azygos lobe holds significant clinical relevance, often mimicking pathological conditions such as pneumothorax or pulmonary bullae on imaging. High-resolution computed tomography (HRCT) enhances its visualization, distinguishing it from disease processes that may prompt unnecessary interventions. Surgically, its presence alters thoracic anatomy, complicating procedures such as video-assisted thoracic surgery (VATS) and lung resections. Despite these challenges, malignancies confined to the azygos lobe have been successfully managed with minimally invasive techniques. This comprehensive review delves into the embryology, anatomy, radiology, clinical implications and surgical considerations of the azygos lobe, underscoring its importance in both diagnostic accuracy and operative planning.