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| IMAGES IN ACADEMIC MEDICINE: REPUBLICATION |
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| Year : 2017 | Volume
: 3
| Issue : 3 | Page : 189-190 |
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The azygos lobe
Jessica Wall1, Stanislaw P Stawicki2
1 Department of Surgery, Division of Critical Care, Trauma, and Burn, The Ohio State University Medical Center, Columbus, OH, USA
2 Department of Surgery, Division of Critical Care, Trauma, and Burn, The Ohio State University Medical Center; OPUS 12 Foundation, Columbus, OH, USA
| Date of Web Publication | 21-Apr-2017 |
Correspondence Address:
Stanislaw P Stawicki
Department of Research and Innovation, St. Luke's University Health Network, EW2 Research Administration, 801 Ostrum Street, Bethlehem, Pennsylvania 18015
USA
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/IJAM.IJAM_10_17
The azygos lobe is a rare anomaly that developmentally arises when the right posterior cardinal vein penetrates the apex of the lung, instead of passing over it, and travels inferiorly taking pleural layers with it to entrap a portion of the right upper lobe. This article reviews the key computed tomography characteristics of azygos lobe, focusing on clinical implications.
The following core competencies are addressed in this article: Medical knowledge.
Republished with permission from: Wall J, Stawicki SP. Interesting clinical image: The azygos lobe. OPUS 12 Scientist 2009;3(2):28-29.
Keywords: Azygos lobe, clinical correlation, computed tomography, significance
How to cite this article:
Wall J, Stawicki SP. The azygos lobe. Int J Acad Med 2017;3, Suppl S1:189-90 |
| Introduction | |  |
The azygos lobe is a rare anomaly that developmentally arises when the right posterior cardinal vein penetrates the apex of the lung, instead of passing over it, and travels inferiorly taking pleural layers with it to entrap a portion of the right upper lobe.[1],[2] The two folds of pleura form the mesoazygos, a fissure visible on 0.4% of chest radiographs and 1.2% of high-resolution computed tomography (CT) studies.[2],[3] The right azygos lobe is supplied by the medial segments of the apical and anterior or posterior branches of the apical segmental bronchial artery and vein.[4],[5] A true left azygos lobe has also been reported.[5],[6]
| Discussion | | |
On chest radiography, the azygos lobe is usually distinguished by the azygos fissure, which superiorly has a triangular shape and inferiorly demonstrates the azygos vein as a tear-shaped shadow.[2],[7] The azygos fissure typically appears as a fine, convex line that crosses the apex of the right lung.[7] The azygos lobe can appear opaque and be incorrectly interpreted as a pathologic mediastinal finding on posteroanterior chest radiographs.[7],[8],[9] When findings on traditional imaging are not clear, CT examinations can be helpful in delineating relevant anatomy [Figure 1]. | Figure 1: Computed tomography of the chest demonstrating the azygos lobe (arrows) from various reference points
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Clinically, the knowledge of azygos lobe anatomy is important during thoracic surgical approaches.[5] Partial obstruction of the thoracoscopic view during a bilateral sympathectomy was reported during attempted mobilization of the azygos lobe.[10],[11] Others reported difficulty in reflecting the pleura during primary repair of the esophageal atresia in a pediatric patient.[12] There are also reports of the phrenic nerve coursing within the azygos fissure.[13] Finally, multiple authors have reported spontaneous pneumothorax associated with the azygos lobe in both adult and pediatric patients.[14],[15],[16],[17],[18]
Acknowledgment
Justifications for re-publishing this scholarly content include: (a) The phasing out of the original publication after a formal merger of OPUS 12 Scientist with the International Journal of Academic Medicine and (b) Wider dissemination of the research outcome (s) and the associated scientific knowledge.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 2. | Mata J, Cáceres J, Alegret X, Coscojuela P, De Marcos JA. Imaging of the azygos lobe: Normal anatomy and variations. AJR Am J Roentgenol 1991;156:931-7. |
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| 13. | Bancroft A, Stephens RE. Course variability of the phrenic nerve in the presence of an azygos lobe: Two case reports. Clin Anat 2007;20:982-3. |
| 14. | Monaco M, Barone M, Barresi P, Carditello A, Pavia R, Mondello B. Azygos lobe and spontaneous pneumothorax. G Chir 2000;21:457-8. |
| 15. | Sadikot RT, Cowen ME, Arnold AG. Spontaneous pneumothorax in a patient with an azygos lobe. Thorax 1997;52:579-80. |
| 16. | Betschart T, Goerres GW. Azygos lobe without azygos vein as a sign of previous iatrogenic pneumothorax: Two case reports. Surg Radiol Anat 2009;31:559-62. |
| 17. | Asai K, Urabe N, Takeichi H. Spontaneous pneumothorax and a coexistent azygos lobe. Jpn J Thorac Cardiovasc Surg 2005;53:604-6. |
| 18. | Rakototiana AF, Rakotoarisoa AJ, Hunald F, Laborde Y. Spontaneous pneumothorax and azygos lobe in a child. Arch Pediatr 2005;12:1406. |
[Figure 1]
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