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Year : 2005  |  Volume : 15  |  Issue : 3  |  Page : 389-393
Pictorial essay : All about bronchial atresia


From the X-ray Clinic, Opp.Commonwealth Bldg., Pune 411030X-ray Clinic, Opp.Commonwealth Bldg., Pune 411030, India

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Keywords: Imaging of bronchial atresia, CT of bronchial atresia, Bronchia

How to cite this article:
Rahalkar A M, Rahalkar M D, Rahalkar M A. Pictorial essay : All about bronchial atresia. Indian J Radiol Imaging 2005;15:389-93

How to cite this URL:
Rahalkar A M, Rahalkar M D, Rahalkar M A. Pictorial essay : All about bronchial atresia. Indian J Radiol Imaging [serial online] 2005 [cited 2020 May 31];15:389-93. Available from: http://www.ijri.org/text.asp?2005/15/3/389/29161

   Introduction Top


Bronchial Atresia ( BA ) is a congenital anomaly of great interest and importance for its varied but classical observations and its semblance to a few, acquired pathological conditions. It can be diagnosed even on plain X-ray of chest but CT can bring out convincingly all related vascular, bronchial, osseous and parenchymal abnormalities.


   Discussion Top


BA was first reported by Ramsay and Byron in 1953 [1] and later on by Simon G & Reid L [2] in 1963. It results from an antenatal vascular insult leading to atresia of a lobar, segmental or even subsegmental bronchus, after 15 th intra-uterine week, at minimum 2 or more levels. Consequently the intervening segments of bronchus or bronchi between the atretic regions form bronchocoeles progressively due to retained secretions leading to mucoid impaction. The lung distal to atresia can develop normally but shows paucity of blood vessels and is hyperinflated due to unilateral collateral air-drift through pores of Kohn and Canals of Lambert from the adjacent normal lung. These collateral channels act as check valves allowing only air to enter and not leave from the distal lung.

BA involves following bronchi in decreasing order of frequency 1. apico-posterior segment of left upper lobe 2. right upper lobe 3. right middle lobe and 4. right lower lobe

BA is detected in most cases incidentally as it is largely asymptomatic. Upto 42 % patients may present with cough, wheezing , haemoptysis, shortness of breath, recurrent infection or pneumothorax etc. BA is surgically dealt with only when it gets complicated by infection.

The radiological appearances are characteristic.

1) Chest X-ray may show a) the bronchocoele, usually close to the hilum, presenting as a tubular, round ,ovoid or branching structure, with or without a fluid level. The branching bronchocoele gives a 'gloved finger' look. Occasionally the dilated bronchi may appear as purely air-filled, lucent bands of odd shapes, e.g. a hairpin [3]. b) the distal lung is always distended, emphysematous and with sparse vascular shadows. This may get infected and present as pneumonia, which may cause tiny breaks in the walls of bronchocoeles and entry of air within its lumen.

c) associated congenital anomalies like hypoplastic ribs or pectus excavatum [1].

2) Bronchography shows non-filling of the involved bronchus. CT will show all the plain film findings even more convincingly and elegantly. The bronchocoele presents as a round/ovoid/branching structure near the hilum, with or without a fluid level, does not enhance and exhibits density of 10 to 25 HU due to mucoid material. The low CT value of thick mucus ( from 10 to 25) and non-enhancing nature of the lesion will exclude any aneurysm or varix.. There are recent reports of application of 3D CT bronchography by using MDCT by Satomi K et al [4]. Their BA had involved right lower lobe.3D CT had helped to comprehend spatial relationship of the branching BA to the bronchi of rest of the lobe, un-suspected on plain X-ray. It can be ascertained that plain X-ray and CT would solve the problem of imaging in all cases.

3) Antenatal USG is said to be able to suspect BA, according to Kamata S et al [5]. BA may be seen as a round, cystic mass (due to fluid collection in the distal lung) with a surrounding small echogenic area. Later on foetal lung liquid escapes, gets replaced by air and BA becomes identifiable.

4) MRI has a limited role, as it can only show very high signal intensity within the bronchocoele on T2W images due to mucoid contents, as reported by Matsushima H et al [6]. MR, however, cannot depict regional air-trapping.

The singular finding of a dilated bronchus due to mucoid impaction, bronchocoele, can be seen in a variety of conditions apart from BA, and they are: bronchial obstruction due to an impacted foreign body/ broncholith, inflammatory stricture, endo-bronchial benign adenoma/malignant tumour/metastasis, extrinsic compression or clinical states such as bronchial asthma, allergic broncho-pulmonary aspergillosis

(ABPA) or mucoviscidosis. All these can produce an appearance of a round, oval or branching (gloved finger) type of bronchocoele. Most of these conditions can be differentiated by appropriate history (as all will be symptomatic), progressive nature of disease, bronchoscopy and biopsy.

It is important in particular to differentiate BA from ABPA. Both will differ on several points, like 1) The patients will always be symptomatic in ABPA, while BA is seen in majority of cases as a chance finding. 2) ABPA is an acquired condition, while BA is a congenital anomaly. 3) ABPA is found in patients of bronchial asthma, while there is no association of asthma in BA. The aspergillus tests and eosinophilia will be seen in the former. 4) In ABPA the radiological findings will be reversible after appropriate treatment, may show progression from multi-focal, non-segmental consolidations to pulmonary fibrosis and central, varicose type of bronchiectasis. The progression and possible complications of BA on the contrary are a continuing process. 5) Lastly BA will remain restricted to only a few segments of predilection and progressive air-trapping & diminished vascularity beyond the bronchocoele are not seen in any other type of bronchocoele.

To sum up BA is easily diagnosed on Chest X-ray by its characteristic appearances and confirmed convincingly by CT, which has the ability to depict its bronchial, vascular, pulmonary and osseous aspects. It is important for general and CT radiologists to know this entity, lest it may be mistaken for pneumonia, focal emphysema, solitary pulmonary nodule, granuloma, complication of asthma such as ABPA, vascular lesion like an aneurysm/varix or abscess. The awareness of this entity would avoid unwarranted surgery in some cases.

CASES

5 cases are presented. All these were asymptomatic, except in case 3, in which pneumonitis had complicated for a short period. There was no history of bronchial asthma or eosinophilia in any of these cases.

Case 1. -Fig.A Chest X-ray shows vague, nodular densities near left hilum with peripheral lucency. Fig. B shows a tomogram revealing a branching structure due the BA.

Case 2. -Fig. A Chest X-ray shows a large complex mass near the left hilum, peripheral emphysema and hypoplastic left 4 th rib. Fig B reveals a branching structure of CT value of 25 to 30. Fig C - This diagram explains how a branching bronchocoele can result from more distal location of atretic process.

Case 3 - Fig A This young child presented with an oval mass near left hilum. Fig B shows development of pneumonia in left upper lobe. Fig C shows complication with formation of air-fluid level in the mass. Fig D shows non-filling of bronchi on bronchography. Fig E explains how this might have occurred.

Case 4 - Fig A and B show a nodular opacity on chest X-ray and tomogram. Fig C reveals non-filling of affected bronchi. Fig. D shows classical features of a branching structure with peripheral lucency.

Case 5 - Fig. A, B and C show features of BA in right upper lobe.

 
   References Top

1.SN Kumar, BS ArunBabu, NK Rabhe et al. Radiological Quiz - Chest. IJRI, 2002; 12:4:574.  Back to cited text no. 1    
2.Simon G and Reid L. Atresia of an apical bronchus of the left upper lobe: Report of three cases. Br J Dis of Chest, 1963; 57:126-132.  Back to cited text no. 2    
3.CJ Zylak, WR Eyler, DL Spizarny et al. Developmental Anomalies in the Adult: Radiologic Pathologic Correlation. Radiographics, 2002; 22: 525-543.  Back to cited text no. 3    
4.Satomi K, Masayuki Y, Shunji T and Atsuka. Bronchial atresia: Three dimensional CT Bronchography using Volume Rendering Technique. Radiation Medicine, 2001;92:2:107-110.  Back to cited text no. 4    
5.Kamata S, Sawai T, Usui N, et al. Case of congenital bronchial atresia detected by antenatal ultrasound. Pediatriac Pulmonol, 2003; 35(3): 9.  Back to cited text no. 5    
6.Matsushima H, Takayagi N. Satoh M et al. Congenital pulmonary atresia : radiological findings in nine patients. J CAT, 2003; 27:103.  Back to cited text no. 6    

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Correspondence Address:
A M Rahalkar
Opp.Commonwealth Bldg., Pune 411030
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-3026.29161

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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]

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