Home About us Editorial board Ahead of print Current issue Search Archives Submit article Instructions Subscribe Contacts Login 
  • Users Online: 250
  • Home
  • Print this page
  • Email this page

 Table of Contents  
Year : 2017  |  Volume : 3  |  Issue : 3  |  Page : 189-190

The azygos lobe

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 Publication21-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
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/IJAM.IJAM_10_17

Rights and Permissions

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

How to cite this URL:
Wall J, Stawicki SP. The azygos lobe. Int J Acad Med [serial online] 2017 [cited 2023 Jan 31];3, Suppl S1:189-90. Available from: https://www.ijam-web.org/text.asp?2017/3/3/189/204942

  Introduction Top

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 Top

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

Click here to view

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]


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


Conflicts of interest

There are no conflicts of interest.

  References Top

Chiba S, Suzuki T, Takahashi D, Kasai T. An autopsy case of azygos lobe and the extra-pulmonary course of the bronchial veins in man. Okajimas Folia Anat Jpn 1990;66:313-37.  Back to cited text no. 1
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.  Back to cited text no. 2
Aziz A, Ashizawa K, Nagaoki K, Hayashi K. High resolution CT anatomy of the pulmonary fissures. J Thorac Imaging 2004;19:186-91.  Back to cited text no. 3
Arakawa T, Terashima T, Miki A. A human case of an azygos lobe: Determining an anatomical basis for its therapeutic postural drainage. Clin Anat 2008;21:524-30.  Back to cited text no. 4
Cimen M, Erdil H, Karatepe T. A cadaver with azygos lobe and its clinical significance. Anat Sci Int 2005;80:235-7.  Back to cited text no. 5
Saeed M, Rufai AA, Osman El-Sayad SE. Lumbar azygos vein producing an azygos lobe in the right lung. Saudi Med J 2002;23:471-3.  Back to cited text no. 6
Caceres J, Mata JM, Andreu J. The azygos lobe: Normal variants that may simulate disease. Eur J Radiol 1998;27:15-20.  Back to cited text no. 7
Cáceres J, Mata JM, Alegret X, Palmer J, Franquet T. Increased density of the azygos lobe on frontal chest radiographs simulating disease: CT findings in seven patients. AJR Am J Roentgenol 1993;160:245-8.  Back to cited text no. 8
Speckman JM, Gamsu G, Webb WR. Alterations in CT mediastinal anatomy produced by an azygos lobe. AJR Am J Roentgenol 1981;137:47-50.  Back to cited text no. 9
Smith J, Karthik S, Thorpe JA. Pulmonary azygous lobe: A potential obstacle during thoracoscopic sympathectomy. Eur J Cardiothorac Surg 2004;25:137.  Back to cited text no. 10
Baumgartner FJ. Thoracoscopic surgery for hyperhidrosis in the presence of congenital azygous lobe and its suspensory web. Tex Heart Inst J 2009;36:44-7.  Back to cited text no. 11
Eradi B, Cusick E. Azygos lobe associated with esophageal atresia: A trap for the unwary. J Pediatr Surg 2005;40:e11-2.  Back to cited text no. 12
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.  Back to cited text no. 13
Monaco M, Barone M, Barresi P, Carditello A, Pavia R, Mondello B. Azygos lobe and spontaneous pneumothorax. G Chir 2000;21:457-8.  Back to cited text no. 14
Sadikot RT, Cowen ME, Arnold AG. Spontaneous pneumothorax in a patient with an azygos lobe. Thorax 1997;52:579-80.  Back to cited text no. 15
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.  Back to cited text no. 16
Asai K, Urabe N, Takeichi H. Spontaneous pneumothorax and a coexistent azygos lobe. Jpn J Thorac Cardiovasc Surg 2005;53:604-6.  Back to cited text no. 17
Rakototiana AF, Rakotoarisoa AJ, Hunald F, Laborde Y. Spontaneous pneumothorax and azygos lobe in a child. Arch Pediatr 2005;12:1406.  Back to cited text no. 18


  [Figure 1]

This article has been cited by
1 Azygos lobe: A rare cause of right paratracheal opacity
Jamal Akhtar,Amos Lal,Kevin B. Martin,Joel Popkin
Respiratory Medicine Case Reports. 2018; 23: 136
[Pubmed] | [DOI]
2 Azygos lobe in a 4-month old infant
Siba P Paul,Julia James
British Journal of Hospital Medicine. 2018; 79(5): 294
[Pubmed] | [DOI]


Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

  In this article
Article Figures

 Article Access Statistics
    PDF Downloaded60    
    Comments [Add]    
    Cited by others 2    

Recommend this journal