A Unique Case of Lung Cancer Invading Azygos Lobe and Vein

Abstract

In human anatomy, an azygos lobe is a congenital variation of the upper lobe of the right lung. It is seen in 1% of the population. Embryologically, it arises from an anomalous lateral course of the azygos vein in a pleural septum within the apical segment of the right upper lobe. As it have no bronchi, veins and arteries of its own or corresponding alteration in the segmental architecture of the lung, so it is not a true (misnomer), or even accessory, pulmonary lobe, but rather an anatomically separated part of the upper lobe. It is usually an incidental finding on chest x-ray or computed tomography and is as such not associated with any morbidity but can cause technical problems in thoracoscopic procedures. This is a case of a 55-year-old male presented to the hospital with cough, right chest pain and clubbing. Chest X-ray revealed a mass in the upper-middle zone of the right lung, and the presence of an azygos lobe. Lung cancer in a patient with azygos lobe invading the azygos vein has not been reported previously. Operative strategy must take in account the anatomy of the azygos vein and its collaterals to avoid intraoperative complications. Invasion of the azygos vein should be added in the T4 group in the next UICC TNM lung cancer staging system