Azygos lobe

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Azygos lobe

An azygos lobe is a rare anatomical variant of the lung. It is not a true lobe but rather an accessory section of the right lung that is separated from the rest of the upper lobe by a deep groove. This groove is formed by the azygos vein as it arches over the apex of the right lung.

Anatomy

The azygos lobe is created during embryological development when the azygos vein fails to migrate over the lung hilum and instead penetrates the upper lobe of the right lung. This results in the formation of a pleural fold that encloses the azygos vein, creating a distinct fissure. The azygos lobe is typically located in the apical segment of the right upper lobe.

Clinical Significance

The presence of an azygos lobe is usually an incidental finding on chest radiography or computed tomography (CT) scans. It is generally asymptomatic and does not require any specific treatment. However, it is important for radiologists and surgeons to be aware of this anatomical variant to avoid misdiagnosis or complications during thoracic surgery.

Imaging

On a chest X-ray, the azygos lobe can be identified by the presence of a fine, curvilinear line that represents the azygos fissure. This line extends from the apex of the right lung towards the mediastinum. On CT scans, the azygos lobe appears as a distinct section of lung tissue separated by the azygos vein.

Associated Conditions

While the azygos lobe itself is benign, it can sometimes be associated with other congenital anomalies or conditions such as tracheal bronchus or esophageal atresia. However, these associations are rare.

See Also

• Lung
• Azygos vein
• Thoracic surgery
• Chest radiography
• Computed tomography