Bronchial Atresia - Symptoms, Diagnosis, and Management

Introduction:

Bronchial atresia is a rare developmental abnormality with narrowing of the lobar, segmental, or subsegmental bronchus. It leads to peripheral mucus impaction and hyperinflation of the obstructed lung segment. It is a congenital malformation that occurs during the formation of the bronchi. It consists of a partial defect of the bronchus, usually at the segmental level, thereby leading to distension of the corresponding pulmonary parenchyma. It is usually asymptomatic and is found incidentally.

The apicoposterior segmental bronchus of the upper left lobe is the most commonly involved lobe, followed by the right upper, middle and lower lobes. It has been associated with other congenital lung disorders, such as congenital cystic adenomatoid malformations, congenital lobar emphysema, and bronchopulmonary sequestration. It has a male predilection over females. It usually shows emphysematous changes in the affected lobe of the lung. These changes are thought to be due to the preserved ventilation through Kohn's pores and Lambert's canals bert in the surrounding lung and bronchi.

What Is the Pathophysiology of Bronchial Atresia?

Fetal lung development shows different stages, like pseudo glandular, canalicular, and saccular stages. Each stage overlaps with the other. Only morphological changes are the main distinguishing feature. The bronchial tree develops between the fifth to seventeenth weeks. During this period, respiratory buds grow outward and divide as adjacent mesenchymal tissues, forming future respiratory channels. No acute or chronic inflammation of the airways and mucus plugging blocking the prominent alveoli and the airway.

What Is the Classical Triad of Bronchial Atresia?

The classical triad of bronchial atresia consist of :

• Sudden obstruction of a segmental bronchus.

• Bronchocele with the "finger in glove" appearance.

• Hyperinflated surrounding lung areas.

What Are the Signs and Symptoms of the Disease?

The disease is usually asymptomatic. However, symptoms seen in very severe cases include:

• Cough.

• Recurrent infections.

• Shortness of breath.

• Wheezing.

• Haemoptysis.

• Chest pain.

• Pneumothorax.

What Are the Diagnostic Tests Done for Bronchial Atresia?

The diagnosis is made based on the following tests:

• Bronchoscopy: It was considered the ideal diagnostic tool previously. A blind-ending bronchus was considered diagnostic for bronchial atresia.

• Chest X-Ray: Rounded, branching opacity in the left upper lung. The presence of perihilar density associated with hyperinflation can be well appreciated on the radiograph.

• Computed Tomography (CT) Scan: It is the gold standard diagnostic tool in the case of bronchial atresia. A characteristic feature is the "finger in glove" appearance due to the branching tubular or nodular opacities radiating from the hilum to the periphery. Segmental hyperlucency in the surrounding lung parenchyma is highly suggestive of congenital bronchial atresia. In some cases, where there are no mucous impactions, only air-filled bronchus is present. The distal lung supplied by the atretic segment can be hyperinflated or hyperlucent due to air trapping and oligemia. The presence of bronchocele and the surrounding emphysema is the typical radiologic finding of bronchial atresia.

• Contrast Enhanced CT Scan: It suggests a dilated central bronchus or bronchocele in the left upper lobe with mucoid impaction of the peripheral bronchi in a branching pattern giving a "finger in glove" appearance.

What Is the Management of Bronchial Atresia?

There is no treatment protocol for the management of bronchial atresia. Typically asymptomatic patients do not require any treatment. Treatment is necessary only in symptomatic patients with secondary complications such as infections or compromised adjacent lung parenchyma. Therefore, only symptomatic relief can be provided.

What Are the Differential Diagnosis of Bronchial Atresia?

The differential diagnosis includes:

• Bronchogenic cyst.

• Pulmonary aplasia.

• Congenital lobar overinflation.

• Congenital cystic adenomatoid malformations.

• Allergic bronchopulmonary aspergillosis.

• Pulmonary sequestration.

• Cystic fibrosis.

• Foreign body aspiration.

• Broncholithiasis.

A bronchogenic cyst is a thin-walled cyst formed by the bronchus's outpouching. It is usually filled with fluid or mucus and typically forms in the middle of the tracheobronchial tree.

Congenital lobar overinflation is a fetal lung developmental anomaly in which air enters the lungs. Still, due to an obstruction in the airways, air cannot leave the lungs, leading to an enlarged, overinflated lung lobe.

Congenital cystic adenomatoid malformations are an infant's most common congenital airway lesion. It usually affects a single lobe of one of the lungs. The cysts are continuous, with the airways filled with fluid in utero and, after birth, filled with air.

Cystic fibrosis is an autosomal recessive disorder that causes sticky, thick, hyper-viscous mucus to build up in the lungs. This mucus secretion is not removed; the secretions plug up ducts and the airways, leading to difficulty breathing and increasing the risk of infections. It is a defect in the cystic fibrosis transmembrane regulator (CFTR) gene. The CFTR is an epithelial anion channel in the alveolar ducts that facilitates the transfer of chloride and bicarbonate ions along with water to pass through it.

Allergic bronchopulmonary aspergillosis is a type of lung disease that occurs in people allergic to a fungus known as aspergillus fumigatus. It is a type of hypersensitivity reaction.

Pulmonary sequestration is the congenital abnormality of the primitive foregut.

What Is the Prognosis of Bronchial Atresia?

Since the disease is asymptomatic, surgery is considered an option only in severe cases with recurrent infections or significant compromise on the adjacent lung parenchyma. The overall prognosis of the disease is excellent.

What Are the Complications of Bronchial Atresia?

The complications include:

• Pneumothorax.

• Recurrent infections.

• Destruction of the lung parenchyma.

Conclusion:

The diagnosis and treatment require a team-based approach. Most of the cases are found incidentally on radiographs. Computed tomography is considered the gold standard diagnostic modality where a characteristic finger-in-glove appearance can be appreciated. The disease is usually asymptomatic, and minimally invasive surgery is considered only in very severe cases with recurrent infections.