A rare anatomical variation detected incidentally on computed tomography of the thorax: the azygos lobe

Abstract

Aim: An azygos lobe is an unusual anatomical variation of the upper lobe of the right lung. During the formation of the lungs, the right azygos lobe develops as the precursor of the azygos vein, moving along the pleural surface rather than arcing forward above the origin of the lung to reach the upper vena cava, enters the apex of the right lung in the upper thoracic region. The purpose of this study was to assess the prevalence of the right azygos lobe in a sample of the Turkish population.

Methods: This study was conducted from February to October 2020. Each computed tomography (CT) scan was checked for the presence of a right azygos lobe and a fissure on the axial plane. The azygos lobe was described as the convex line in the paramediastinal portion of the upper right lung on the CT scan. Our exclusion criteria were previous thoracic surgery in the right lung or parenchymal distortion on CT examinations.

Results: One thousand nine hundred and sixty-five thorax CT scans were evalu¬ated retrospectively. Nine hundred and forty-five of them were from men and the remainder were from women. A total of 15 right azygos lobe variations were detected (six females, nine males). The mean age of the patients was 52.87 ± 14.604 years (30–77). The azygos lobe frequency was 0.76%.

Conclusion: The azygos lobe is typically an uncommon variation of the right lung and is not really a distinct lobe. It is a very important variation that should be known about as it can mimic pathological conditions such as cysts, abscesses, or lung le¬sions. Since the azygos lobe is usually an incidental finding, radiologists and sur¬geons should be aware of this this potential anomaly during the imaging and inter¬ventional procedures.