Azygos lobe

Azygos lobe on chest x-ray. Arrowheads show the delineation of the lobe. Arrow points to the azygos vein.

Azygos lobe in axial computertomography. Arrow on azygos vein.

In human anatomy, an azygos lobe is a rare congenital variation of the upper lobe of the right lung. Embryologically, it arises from an anomalous lateral course of the azygos vein [1] [2] in a pleural septum within the upper lobe. As it has no bronchi, veins and arteries of its own, it is not a true, 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 [3].

Further reading

• Mata J, Cáceres J, Alegret X, Coscojuela P, De Marcos JA (May 1991). "Imaging of the azygos lobe: normal anatomy and variations". AJR Am J Roentgenol 156 (5): 931–7. PMID 2017954. http://www.ajronline.org/cgi/reprint/156/5/931.pdf.