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CHEST IMAGE
Year : 2021  |  Volume : 9  |  Issue : 1  |  Page : 49-50

An unusual cause of right upper zone opacity − azygous fissure


Department of Pulmonary Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India

Date of Submission01-Jun-2020
Date of Decision04-Jul-2020
Date of Acceptance11-Aug-2020
Date of Web Publication15-Feb-2021

Correspondence Address:
Dr. G. Vishnukanth
Associate Professor, Department of Pulmonary Medicine Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry 605006
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jacp.jacp_32_20

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  Abstract 


Azygous lobe is a normal congenital anatomic variant of the right upper lobe. The azygos lobe is not anatomically a separate lobe. Radiologically azygous lobe is noted in the apicomedial region of the right lung and is separated from the rest of upperlobe by azygous fissure. Though not a pathology, azygous lobe can be mistaken for a lung abscess or a bulla. Other complications include hemoptysis or azygous vein aneurysm.

Keywords: Azygous lobe, triagonum parietale


How to cite this article:
Vishnukanth G, Ravindra AG, Selvaraja C, Narenchandra V. An unusual cause of right upper zone opacity − azygous fissure. J Assoc Chest Physicians 2021;9:49-50

How to cite this URL:
Vishnukanth G, Ravindra AG, Selvaraja C, Narenchandra V. An unusual cause of right upper zone opacity − azygous fissure. J Assoc Chest Physicians [serial online] 2021 [cited 2021 Apr 20];9:49-50. Available from: https://www.jacpjournal.org/text.asp?2021/9/1/49/309472




  Case details Top


A forty year old lady was referred for chest x ray opinion prior to starting immunosuppression. She had no significant respiratory illness in the past. Her chest x ray was a rotated film and was predominantly normal except for a curvilinear opacity in the right upper zone adjacent to the mediastinum [Figure 1]. The lower part of the opacity was pear shaped/tear drop shaped. A possibility of azygous fissure was considered and a contrast CT thorax was done. CT showed the presence of azygous lobe and azygous fissure containing the azygous vein [Figure 2].
Figure 1 Chest x ray PA view showing a curvilinear opacity in the right upper zone

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Figure 2 Contrast CT of the upper thorax showing curvilinear azygous fissure with the azygous vein enclosed

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  Discussion Top


Azygous lobe is a normal congenital anatomic variant usually of the right upper lobe. It was first described by Heinrich Wrisberg in 1778.[1] The prevalence of azygous lobe is less than 0.5% on chest x ray and 1% on high resolution CT scans.[2] Though always a right sided entity, left sided azygous lobe has also been reported.[3] Azygous lobe is formed when the right posterior cardinal vein, a precursor of the future azygous vein penetrates the right lung apex, rather than migrating over it. The azygos lobe is not anatomically a separate lobe as it neither has its own bronchus nor correspond to a specific bronchopulmonary segment.[4]

Radiologically azygous lobe is noted in the apicomedial region of the right lung and is separated from the rest of upperlobe by azygous fissure. The azygous fissure is observed as a fine, convex line on chest x ray in the para mediastinal portion of the right lung. The upper most part of the fissure is triangular in shape and is referred as “triagonum parietale” that contains a small amount of areolar tissue between the parietal layers of pleura. The lower most portion of the azygos fissure is seen as tear drop opacity and usually contains the azygos vein.[4] Though not a pathology, azygous lobe can be mistaken for a lung abscess or a bulla. Other complications include hemoptysis or azygous vein aneurysm.[5],[6]

Acknowledgement

The authors would like to acknowledge the help rendered by Dr. Dharm Prakash Dwivedi, Associate Professor and Dr. Sahana Junior resident of pulmonary medicine, JIPMER in helping with the research and preparation of manuscript.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Ndiaye A, Ndiaye NB, Ndiaye A, Diop M, Ndoye JM, Dia A. The azygos lobe: an unusual anatomical observation with pathological and surgical implications. Anat Sci Int 2012;87:174-8.  Back to cited text no. 1
    
2.
Mata J, Jose C, 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
    
3.
Takasugi JE, Godwin JD. Left azygos lobe. Radiology 1989;171:133-4.  Back to cited text no. 3
    
4.
Akhtara J, Lala A, Martinb KB, Popkina J. Azygos lobe: a rare cause of right paratracheal opacity. Respiratory Medicine Case Reports 2018;23:136-7  Back to cited text no. 4
    
5.
Icard P, Fares E, Regnard JF, Levasseur P. Thrombosis of an idiopathic saccular azygos aneurysm. Eur J Cardio-Thorac Surg 1999;15:870-2  Back to cited text no. 5
    
6.
Denega T, Alkul S, Islam E, Alalawi R. Recurrent hemoptysis − a complication associated with an azygos lobe. Southwest Respir Crit Care Chronicles 2015;3.  Back to cited text no. 6
    


    Figures

  [Figure 1], [Figure 2]



 

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