Bronchial Atresia

Jud W. Gurney, MD, FACR

Key Facts

Terminology

Congenital atresia of segmental bronchus with normal distal architecture

Imaging Findings

Apicoposterior segment left upper lobe (50%), followed by right upper lobe (20%), lower lobes (15% each), and rarely right middle lobe (< 5%)
Typical triad
- Central nodule or mass representing mucoid impaction distal to atretic bronchus (bronchocele)
- Hyperlucency of affected segment
- Hypoperfusion of affected segment with paucity of vessels
Bronchocele
- Blunt horn-like protrusions distal to mass (mucoid impaction in bronchiectatic bronchi)
- Occasionally have air-fluid level

Top Differential Diagnoses

Mucoid Impaction with Hyperinflation
Congenital Lobar Emphysema
Intralobar Pulmonary Sequestration

Pathology

2nd most common congenital tracheobronchial malformation after pulmonary sequestration
2 theories of pathogenesis
- Disconnected cells from bronchial bud
- Intrauterine vascular injury

Diagnostic Checklist

Exclude slow-growing endobronchial tumor

Coronal graphic shows bronchial atresia

with branching bronchocele

in the apical segment left upper lobe.

Coronal CECT shows focal lucency

from bronchial atresia and central mucus-filled bronchocele

in this patient with segmental bronchial atresia.

TERMINOLOGY

Abbreviations and Synonyms

Mucocele

Definitions

Congenital atresia of segmental bronchus with normal distal architecture

IMAGING FINDINGS

General Features

Best diagnostic clue: Round, sharply-defined, perihilar mass with distal hyperinflation
Patient position/location
- Apicoposterior segment left upper lobe (50%)
  - Followed by right upper lobe (20%), lower lobes (15% each) and rarely right middle lobe (< 5%)
Size: Bronchocele usually > 1 cm in diameter
Morphology: Atretic bronchus usually segmental but may be lobar or distally in subsegmental airways

CT Findings

Triad: Bronchocele and hyperlucent and hypoperfused segment diagnostic of bronchial atresia
Bronchocele
- May be of lower attenuation due to mucoid material
- May contain calcium
- No enhancement
- Shape: Tubular, spherical, branching
- Bronchocele aligned along central axis of affected segment
- Bronchocele located medial to hyperinflated lung
- Wedge-shaped hyperinflated lung surrounds bronchocele
Rare systemic arterial supply (bronchoarterial malinosculation)

Radiographic Findings

Radiography
- Typical triad
  - Central nodule or mass representing mucoid impaction distal to atretic bronchus (bronchocele)
  - Hyperlucency of affected segment
  - Hypoperfusion of affected segment with paucity of vessels
- Bronchocele
  - Sharply defined rounded or tubular branching opacities adjacent to the hilum (teardrops, grape-like clusters, gloved-finger appearance)
  - Bronchocele points towards hilum
  - Blunt horn-like protrusions distal to mass (mucoid impaction in bronchiectatic bronchi)
  - Occasionally have air-fluid level
- Hyperlucent lobe
  - Neonates: Lobe or segment distal to atretic bronchus fluid-filled, gradually replaced by air
  - Resorption of fluid occurs within 1st week of life
  - Ventilation from collateral air drift via intraalveolar pores of Kohn and bronchoalveolar channels of Lambert across incomplete intrapulmonary fissures
- Boomerang sign
  - Parabolic curve: Junction of hyperinflated segment with adjacent normal lung
- Associated findings
  - Hypoplastic ribs, pectus excavatum

Ultrasonographic Findings

Can be detected in utero
Fluid-filled upper lobe
- Differential
  - Cystic adenomatoid malformation
  - Congenital diaphragmatic hernia
  - Bronchopulmonary foregut malformations
  - Congenital lobar emphysema

Nuclear Medicine Findings

V/Q scan
- Hypoperfusion of affected segment
- Delayed ventilation of affected segment with delayed washout (air-trapping)

Imaging Recommendations

Best imaging tool: CT procedure of choice to characterize bronchocele, airway anatomy, and distal hyperinflated lung and other associated anomalies
Protocol advice
- Expiratory CT demonstrates accentuated hyperinflation of affected segments
- Multidetector CT useful in demonstrating anatomy of atretic bronchus

DIFFERENTIAL DIAGNOSIS

Mucoid Impaction with Hyperinflation

Bronchial atresia
Intralobar sequestration
Intrapulmonary bronchogenic cyst

Congenital Lobar Emphysema

No bronchocele
Left upper lobe also most commonly affected
Hyperinflated lobe causes mass effect with shift of mediastinum away from affected lobe
Usually diagnosed in infancy with respiratory distress

Intralobar Pulmonary Sequestration

May have distal hyperinflation
Abnormal systemic arterial supply, usually from aorta
Most common location is left lower lobe in paravertebral angle

Intrapulmonary Bronchogenic Cyst

Usually located in medial 1/3 of lung in lower lobes
May have distal hyperinflation
Cyst may be fluid-filled, air-filled, or both (air-fluid level)

Arteriovenous Malformation

Abnormal feeding artery and draining vein
Nodule will enhance with contrast administration
No bronchial obstruction, no hyperlucency or hyperinflation

Mucoid Impaction Associated Conditions

Endobronchial lesion
- Bronchogenic carcinoma
- Extrinsic compression
- Foreign body
Inflammatory
- Tuberculosis
- Cystic fibrosis
- Asthma
- Allergic bronchopulmonary aspergillosis

Allergic Bronchopulmonary Aspergillosis

Central bronchiectasis with mucoid impaction
Diffuse, not localized
Primarily affects upper lung zones
Distal lung usually abnormal
- Small airways disease: Tubular branching opacities, hyperinflation