Bronchial Atresia
Jud W. Gurney, MD, FACR
Key Facts
Terminology
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Congenital atresia of segmental bronchus with normal distal architecture
Imaging Findings
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Apicoposterior segment left upper lobe (50%), followed by right upper lobe (20%), lower lobes (15% each), and rarely right middle lobe (< 5%)
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Typical triad
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Central nodule or mass representing mucoid impaction distal to atretic bronchus (bronchocele)
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Hyperlucency of affected segment
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Hypoperfusion of affected segment with paucity of vessels
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Bronchocele
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Blunt horn-like protrusions distal to mass (mucoid impaction in bronchiectatic bronchi)
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Occasionally have air-fluid level
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Top Differential Diagnoses
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Mucoid Impaction with Hyperinflation
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Congenital Lobar Emphysema
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Intralobar Pulmonary Sequestration
Pathology
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2nd most common congenital tracheobronchial malformation after pulmonary sequestration
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2 theories of pathogenesis
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Disconnected cells from bronchial bud
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Intrauterine vascular injury
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Diagnostic Checklist
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Exclude slow-growing endobronchial tumor
TERMINOLOGY
Abbreviations and Synonyms
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Mucocele
Definitions
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Congenital atresia of segmental bronchus with normal distal architecture
IMAGING FINDINGS
General Features
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Best diagnostic clue: Round, sharply-defined, perihilar mass with distal hyperinflation
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Patient position/location
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Apicoposterior segment left upper lobe (50%)
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Followed by right upper lobe (20%), lower lobes (15% each) and rarely right middle lobe (< 5%)
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Size: Bronchocele usually > 1 cm in diameter
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Morphology: Atretic bronchus usually segmental but may be lobar or distally in subsegmental airways
CT Findings
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Triad: Bronchocele and hyperlucent and hypoperfused segment diagnostic of bronchial atresia
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Bronchocele
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May be of lower attenuation due to mucoid material
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May contain calcium
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No enhancement
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Shape: Tubular, spherical, branching
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Bronchocele aligned along central axis of affected segment
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Bronchocele located medial to hyperinflated lung
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Wedge-shaped hyperinflated lung surrounds bronchocele
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Rare systemic arterial supply (bronchoarterial malinosculation)
Radiographic Findings
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Radiography
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Typical triad
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Bronchocele
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Sharply defined rounded or tubular branching opacities adjacent to the hilum (teardrops, grape-like clusters, gloved-finger appearance)
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Bronchocele points towards hilum
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Blunt horn-like protrusions distal to mass (mucoid impaction in bronchiectatic bronchi)
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Occasionally have air-fluid level
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Hyperlucent lobe
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Neonates: Lobe or segment distal to atretic bronchus fluid-filled, gradually replaced by air
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Resorption of fluid occurs within 1st week of life
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Ventilation from collateral air drift via intraalveolar pores of Kohn and bronchoalveolar channels of Lambert across incomplete intrapulmonary fissures
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Boomerang sign
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Parabolic curve: Junction of hyperinflated segment with adjacent normal lung
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Associated findings
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Hypoplastic ribs, pectus excavatum
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Ultrasonographic Findings
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Can be detected in utero
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Fluid-filled upper lobe
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Differential
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Cystic adenomatoid malformation
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Congenital diaphragmatic hernia
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Bronchopulmonary foregut malformations
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Congenital lobar emphysema
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Nuclear Medicine Findings
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V/Q scan
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Hypoperfusion of affected segment
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Delayed ventilation of affected segment with delayed washout (air-trapping)
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Imaging Recommendations
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Best imaging tool: CT procedure of choice to characterize bronchocele, airway anatomy, and distal hyperinflated lung and other associated anomalies
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Protocol advice
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Expiratory CT demonstrates accentuated hyperinflation of affected segments
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Multidetector CT useful in demonstrating anatomy of atretic bronchus
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DIFFERENTIAL DIAGNOSIS
Mucoid Impaction with Hyperinflation
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Bronchial atresia
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Intralobar sequestration
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Intrapulmonary bronchogenic cyst
Congenital Lobar Emphysema
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No bronchocele
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Left upper lobe also most commonly affected
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Hyperinflated lobe causes mass effect with shift of mediastinum away from affected lobe
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Usually diagnosed in infancy with respiratory distress
Intralobar Pulmonary Sequestration
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May have distal hyperinflation
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Abnormal systemic arterial supply, usually from aorta
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Most common location is left lower lobe in paravertebral angle
Intrapulmonary Bronchogenic Cyst
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Usually located in medial 1/3 of lung in lower lobes
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May have distal hyperinflation
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Cyst may be fluid-filled, air-filled, or both (air-fluid level)
Arteriovenous Malformation
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Abnormal feeding artery and draining vein
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Nodule will enhance with contrast administration
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No bronchial obstruction, no hyperlucency or hyperinflation
Mucoid Impaction Associated Conditions
Allergic Bronchopulmonary Aspergillosis
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Central bronchiectasis with mucoid impaction
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Diffuse, not localized
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Primarily affects upper lung zones
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Distal lung usually abnormal
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Small airways disease: Tubular branching opacities, hyperinflation
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Cystic Fibrosis
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Central bronchiectasis
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Bilateral disease usually more severe in upper lung zones, especially right upper lobe
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May have mucoid impaction
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Distal lung usually abnormal
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