Radiology Teaching Files > Case 159134

Contributed by: Safwan Halabi, Resident, Cincinnati Children's Hospital Medical Center, Ohio, USA.
Patient: 49 year old male
History: Chest pain.

Fig. 1

Fig. 2
Findings: Curvilinear opacity in the right upper lung extending from the right apex to the right mediastium.
Diagnosis: Azygos lobe of the right lung.

An azygos lobe of right lung is a small accessory lobe sometimes formed above the hilum of the right lung; separated from the rest of the upper lobe by a deep groove lodging the azygos vein. Syn: lobus azygos pulmonis dextri. A small accessory lobe sometimes found on the upper part of the right lung; separated from the rest of the upper lobe by a deep groove lodging the azygos vein, of little clinical significance.

Radiographic Appearance

The azygos lobe appears starting in a teardrop shape at around the level of T5 to the right of the midline as a pale line curving outward and upward and then back in to meet the root of the neck, the line is the infolding of the pleura.


Abnormal fissures and lobes of the lungs are common and usually insignificant. A lobe of the azygos vein appears in the right lung in about 1 percent of people. It develops when the apical bronchus grows superiorly medial to the arch of the azygos vein instead of lateral to it. As a result, the azygos vein comes to lie at the bottom of a deep fissure in the superior lobe of the right lung. Therefore, the azygos fissure contains four layers of pleura.


No treatment is required


1. Stedman's Medical Dictionary (Referenced 9/19/03)
2. (Referenced 9/22/03)

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Additional Details:

Case Number: 159134Last Updated: 09-22-2003
Anatomy: Lung   Pathology: Normal/Variants
Modality: Conventional RadiographExam Date: 09-19-2003Access Level: Readable by all users
Keywords: azygos lobe

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