As regard human anatomy the azygos lobe is considered a congenital anomaly of the upper lobe of the right lung. In embryolog, the pleural septum of the upper lobe the lateral course of azygos vein arises in abnormal manner. It considered not a true lobe as it has no vessels, bronchi or even accessory, pulmonary lobe, but considered separated part of the upper lobe. It is usually discovered accidentally on chest x-ray or computed tomography and is not associated with any morbidity but can cause technical problems in thoraco-scopic maneuvers.
Conclusion and Clinical Message
Azygos vein laterally displaced into apical segment of right upper lobe leading to deep pleural fissure during embryological development resulting in formation of azygos lobe. No problem or disease result from this anatomical variant but must be considered during thoracic surgeries as also it is not even accessory lobe as it does not has normal structures of true lobe. Azygos lobe is found in 1% of anatomic specimens .