Bronchial Atresia

Bronchial atresia is a congenital interruption of a segmental, subsegmental or lobar bronchus, with a blind ending proximal stump and normal distal lung that fills by collateral ventilation. Mucus collects beyond the stump as a mucocele, and the lung beyond is hyperinflated.

The apicoposterior segment of the left upper lobe is involved in about two thirds, followed by the segments of the right upper, middle and lower lobes. Most patients are asymptomatic and diagnosed on a radiograph in adolescence or young adulthood, and symptoms are usually from infection.

Pathophysiology. Focal obliteration of a bronchus during embryonic development leaves distal bronchi that are patent and filled with mucus. Air enters the distal lung through the pores of Kohn and canals of Lambert, but is trapped, and the result is segmental hyperinflation with reduced vascularity.

Most have no symptoms. Others have wheeze, cough, breathlessness on exertion, recurrent infection in the affected segment and, rarely, haemoptysis. Examination is usually normal, with reduced breath sounds and hyper-resonance over the segment.

Fever with chest pain and sputum suggests infection of the mucocele and needs prompt treatment.

• Chest radiograph: a rounded or branching perihilar opacity (the mucocele) with a surrounding area of hyperlucency.
• CT chest (the key test): bronchocele, hyperinflated segment with reduced vascular markings, and no connection of the mucocele to the central airway. CT also looks for associated malformations.
• Flexible bronchoscopy to show a blind pouch and to exclude an endobronchial obstruction, in selected cases.
• Spirometry, usually normal.
• Distinguish from endobronchial obstruction by a tumour (carcinoid), foreign body or tuberculous stricture, which can look identical on imaging; from pulmonary sequestration and congenital pulmonary airway malformation (look for feeding vessel and cysts); and from allergic bronchopulmonary aspergillosis with mucoid impaction (asthma, eosinophilia, raised IgE, central bronchiectasis).

• Asymptomatic: observation with no treatment, and an explanation of infection warning features. Repeat imaging only when symptoms change.
• Infection: amoxicillin-clavulanate 625 mg orally three times daily for 7 to 10 days in adults (reduce to 625 mg every 12 hours at eGFR 10 to 30), and weight based dosing in children. Doxycycline 100 mg twice daily in penicillin allergy.
• Surgery by thoracoscopic or open segmentectomy or lobectomy for recurrent infection, haemoptysis, large mucocele with compression, or diagnostic uncertainty about a tumour. Resection is curative, and adjacent lung is spared where possible.
• In children, surgery is delayed until after infancy unless there is respiratory distress, and a repeat CT is done before operating.
• Smoking avoidance and vaccination against influenza and pneumococcus.

Complications and prognosis. Recurrent infection and rarely abscess. Outcome is excellent, and most patients live without limitation.

Monitoring. Clinical review yearly for those not operated, and after surgery with a chest radiograph at 3 months.

Referral and escalation. Refer to a respiratory or thoracic surgeon when symptoms or infection occur, or when imaging cannot exclude an obstructing lesion.