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CASE REPORT
Year : 2019  |  Volume : 8  |  Issue : 2  |  Page : 141-142

Azygos lobe and partial eventration of diaphragm


Department of TB and Chest Diseases, RIMS Medical College, Ongole, Andhra Pradesh, India

Date of Submission25-Feb-2016
Date of Acceptance06-Sep-2018
Date of Web Publication30-Jul-2019

Correspondence Address:
Dr. Srikanti Raghu
Department of TB and Chest Diseases, RIMS Medical College, Ongole, Andhra Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/JDRNTRUHS.JDRNTRUHS_30_16

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  Abstract 


An azygos lobe is an accessory lobe of the lung that may occasionally be confused with a pathological process such as a bulla, lung abscess, or neoplasm. Eventration of the diaphragm is generally regarded as a condition in which the left or the right leaf of the diaphragm has ascended abnormally high into the chest. In this case, both eventration of diaphragm and azygos lobe presented in the same patient on the same side.

Keywords: Accessory lobe, azygos lobe, eventration, lung


How to cite this article:
Raghu S. Azygos lobe and partial eventration of diaphragm. J NTR Univ Health Sci 2019;8:141-2

How to cite this URL:
Raghu S. Azygos lobe and partial eventration of diaphragm. J NTR Univ Health Sci [serial online] 2019 [cited 2019 Aug 25];8:141-2. Available from: http://www.jdrntruhs.org/text.asp?2019/8/2/141/263633




  Introduction Top


The lungs are normally divided into five lobes by three main fissures. Occasionally, invaginations of the visceral pleura create accessory fissures that separate individual bronchopulmonary segments into accessory lobes.[1] An azygos lobe is found in approximately 0.4% of patients.[2] In contrast to other accessory lobes, the azygos lobe does not correspond to a distinct anatomical bronchopulmonary segment.[1],[3] It forms during embryogenesis when the precursor of the azygos vein fails to migrate to its medial position in the mediastinum, where it normally arches over the origin of the right upper lobe bronchus.[1],[2],[3] Eventration of the diaphragm is generally regarded as a condition in which the left or the right leaf of the diaphragm has ascended abnormally high into the chest. In rare cases, both leaves are elevated. The elevated leaf may appear almost normal or show degeneration of varying degree; it may even be a thin, translucent membrane without muscular fibers. The eventration may be total or partial.


  Case History Top


A 45-year-old female presented to us with complaints of cough with expectoration and on and off fever since 1 week. General physical examination was normal. Tactile vocal fremitus was decreased and note was impaired on the right side. Breath sounds were decreased in the right inframammary, infra-axillary, and infrascapular areas.

Laboratory investigations were within normal limits. Chest X-ray showed a homogeneous opacity in the right lower zone plus azygos fissure on the right side.


  Discussion Top


An azygos lobe is found in approximately 0.4% of patients.[2] In contrast to other accessory lobes, the azygos lobe does not correspond to a distinct anatomical bronchopulmonary segment.[1],[3] It forms during embryogenesis when the precursor of the azygos vein fails to migrate to its medial position in the mediastinum, where it normally arches over the origin of the right upper lobe bronchus.[1],[3] This gives rise to the following characteristics, which are visible on a standard chest X-ray [Figure 1]: the laterally displaced azygos vein lies between folds of parietal pleura, also referred to as the mesoazygos, where it assumes a characteristic teardrop shape;[2],[3] the mesoazygos indents the right upper lobe, thereby creating the accessory (azygos) fissure, which is similar in shape to an inverted comma; the fissure delineates the azygos lobe, located superomedially;[1],[2],[3] laterally, the pleural folds of the mesoazygos separate before reaching the chest wall, resulting in a radiopaque triangular area;[2],[3] and medially, the tracheobronchial angle appears empty.[2]
Figure 1: Chest X-Ray PA View showing azygous lobe and eventration of diaphragm

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An azygos lobe may be confused with a pathological air space such as a bulla or abscess.[2],[3] In addition, the abnormally located azygos vein may be mistaken for a pulmonary nodule, while a consolidated azygos lobe may be confused with a mass.[3] An understanding of the pathogenesis and characteristic X-ray features of the azygos lobe will enable an accurate diagnosis in most cases.[1],[2],[3] If the X-ray findings are equivocal, computed tomography will be diagnostic.[3]

Eventration of the diaphragm is a condition in which all or part of the diaphragm is largely composed of fibrous tissue with only a few or no interspersed muscle fibers. It is usually congenital but may be acquired.[4]

Complete eventration of diaphragm invariably occurs on the left side, but partial eventration of the diaphragm occurs virtually on the right side. In this case, the complete eventration of diaphragm was seen on the right side which is a rarity. Eventration of diaphragm is generally asymptomatic in adults and is discovered incidentally on normal screening of chest X-ray as was in the present case. Symptoms may be present in obese patients as a result of raised intra-abdominal pressure. These symptoms, related to gastrointestinal tract, respiratory embarrassment, and rarely cardiac dysfunction, have been attributed to the anomaly.[5]

In the present case, both eventration of diaphragm and azygos lobe presented in the same patient on the same side which is relatively uncommon.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Shields TW, Locicero J, Reed CE, Feins RH. General Thoracic Surgery, 7th ed.. Chicago, IL: Lippincott Williams and Wilkins; 2009: p. 72-3.  Back to cited text no. 1
    
2.
Felson B. The azygos lobe: Its variation in health and disease. Semin Roentgenol 1989;24:56-66.  Back to cited text no. 2
    
3.
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. 3
    
4.
Laxdale OE, McDougall H, Mellin GW. Congenital eventration of the diaphragm. N Engl Med 1954;250:401.  Back to cited text no. 4
    
5.
Chin EF, Lynn RB. Surgery of eventration of the diaphragm. J Indian Med 1986;84:187.  Back to cited text no. 5
    


    Figures

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