Prevalence of Azygos Lobe of the Lung in Southern Indian Cadaveric Population: A Retrospective Observational Study

Abstract

Introduction: The azygos lobe is a developmental anomaly found in the upper lobe of the right lung. It has a prevalence of 0.4% in clinical scenarios and 1% during routine anatomical dissections. Clinically, the azygos lobe mimics various conditions. It is a rare incidental finding during chest radiography or Computed Tomography (CT). Aim: To determine the prevalence of the azygos lobe during anatomical dissection. Materials and Methods: A retrospective observational study was conducted over a 13-year period from June 2010 to August 2023 in various medical colleges in Mangaluru, Karnataka, India. A total of 102 adult cadavers were studied. The dissected right and left lungs of each cadaver were examined for the presence or absence of an azygos lobe and recorded. The morphology of the azygos lobe was studied, including its size, the presence of the azygos fissure, the depth of the azygos fissure, and the course of the azygos vein. The presence of mesoazygos was also checked, and its attachments were noted. Descriptive statistics were used in terms of frequency and percentage. Results: Out of the 102 cadavers, only one right lung had an azygos lobe. None of the cadavers had bilateral azygos lobes. The maximum height of the lobe was 5.8 cm, and the width was 4.5 cm. An azygos fissure was found, through which the mesoazygos was present. The mesoazygos was located from the lung to the thoracic wall. Conclusion: Despite being an incidental finding, the azygos lobe is clinically important. Physicians should be aware of this anomaly, and thoracic surgeons should exercise caution during surgeries involving the thoracic region, such as Video-Assisted Thoracic Sympathectomy (VATS).