Azygos lobe retrospective evaluation

Aim: The azygos lobe is a well-known anatomical variation of the lung, formed due to the aberrant course of the azygos vein during fetal development. The incidence of the azygos lobe has been reported to be between 0.4% and 1%. This study aims to identify the prevalence of the azygos lobe in a specific patient population, classify its variations, and highlight its importance in differential diagnosis and associated pathologies. Methods: A retrospective analysis was conducted on 4,549 patients who visited our pulmonology clinic between April 2014 and November 2017. The presence of an azygos lobe was identified through radiological screening. Results: Among the 4,549 patients screened, 14 cases (0.31%) of azygos lobe were detected, comprising 10 males and four females. The azygos lobe was classified based on the course of the azygos fissure: Type A (lateral to the lung apex) in seven cases (50%), Type B (midline and more vertical) in three cases (21%), and Type C (medial, extending into the mediastinum) in four cases (29%). Additionally, 12 cases (85.7%) were located on the right side, while two cases (14.3%) were on the left. Conclusions: The azygos lobe is most commonly detected incidentally during imaging for unrelated conditions. Our study emphasizes the importance of recognizing the azygos lobe as a differential diagnosis and investigating potential coexisting pathologies. The findings contribute to existing statistical data on the prevalence and anatomical variations of the azygos lobe.