Williams-Campbell Syndrome: Comprehensive Imaging Guide and Clinical Overview
Overview
Williams-Campbell Syndrome is a rare congenital disorder named after William and Campbell, who first described it in 1948 based on two pediatric patients with distinctive bronchial cartilage deficiency leading to bronchiectasis.
The naming rationale reflects the bronchoscopic and pathological findings of absent cartilage rings in subsegmental bronchi, distinguishing it from other cystic lung diseases.
Clinically, patients present with recurrent pneumonia, chronic cough, wheezing, and dyspnea, often with hyperinflation on exam; pediatric cases predominate, but adult-onset acquired forms occur post-viral infection.
There is no defined inheritance pattern, though it is primarily congenital with rare familial reports; acquired variants suggest post-infectious etiology in adults.
Key Imaging Features
- Williams-Campbell Syndrome manifests on chest radiographs as bilateral hyperinflated lungs with increased radiolucency, scattered thin-walled cystic lucencies, and central bronchiectasis, often with air trapping or atelectasis.
- Inspiratory CT shows characteristic ballooning of cystic, thin-walled bronchiectasis involving fourth- to sixth-order bronchi bilaterally, with normal trachea and proximal mainstem bronchi.
- Expiratory CT demonstrates dramatic collapse (up to 80%) of affected bronchi, confirming cartilage deficiency, while peripheral airways remain spared.
- Three-dimensional CT reconstructions reveal absence of cartilage ring impressions in subsegmental bronchi, with distal airway collapse and central cystic changes.
- Minimum intensity projection (MinIP) coronal views highlight cystic bronchiectasis distal to third-generation bronchi, with hyperinflation and bronchial wall thinning.
- Dynamic free-breathing CT captures inspiratory expansion and expiratory collapse of middle-order and distal mainstem bronchi in Williams-Campbell Syndrome.
- Imaging evolution over time shows progressive bronchiectasis with repeated infections, though proximal bronchi remain unaffected lifelong.
Pathophysiology
In Williams-Campbell Syndrome, defective or absent cartilage in subsegmental bronchi (typically fourth to sixth order) leads to loss of structural rigidity in the bronchial wall anatomy.
During inspiration, positive pressure causes ballooning dilatation of these flaccid airways, forming thin-walled cystic bronchiectasis visible on inspiratory CT.
On expiration, the cartilage-deficient bronchi collapse nearly completely due to lack of supportive rings, trapping air distally and causing hyperinflation—a hallmark pathological process in tracheobronchial tree dynamics.
This results in recurrent infections from impaired mucociliary clearance, worsening bronchiectasis over time; adult cases may involve post-viral cartilage degradation mimicking congenital deficiency.
Pearl: Measure bronchial collapse as >50% diameter reduction on paired inspiratory-expiratory CT scans for confirmation; pitfall—motion artifact can mimic collapse, necessitating controlled breathing protocols.
Differential Diagnosis
| Condition | Distinguishing Imaging Features from Williams-Campbell Syndrome |
|---|---|
| Tracheobronchomalacia | Affects trachea and mainstem bronchi with collapse; spares subsegmental bronchi, unlike central fourth-to-sixth order involvement. |
| Mounier-Kuhn Syndrome | Tracheal and proximal bronchial megaly with redundant mucosa; collapse less severe (<50%), peripheral airways normal but no cystic subsegmental changes. |
| Allergic Bronchopulmonary Aspergillosis (ABPA) | Central bronchiectasis with mucoid impaction and high-attenuation mucus; lacks dynamic collapse, shows finger-in-glove opacities absent in Williams-Campbell Syndrome. |
| Cystic Fibrosis | Diffuse upper lobe predominant bronchiectasis involving peripheral airways; no selective subsegmental cartilage loss or expiratory collapse pattern. |
| Swyer-James Syndrome | Unilateral hyperlucency with small lung/artery; no bilateral cystic central bronchiectasis or dynamic collapse. |
Pearl: Expiratory CT collapse >80% in central bronchi favors Williams-Campbell Syndrome; pitfall—confuse with infection-exacerbated bronchiectasis without dynamic imaging.
Imaging Protocols and Techniques
For suspected Williams-Campbell Syndrome, initiate with chest radiograph (PA/lateral) to detect hyperinflation and cystic lucencies.
Primary modality: paired inspiratory-expiratory thin-section CT (1-1.5mm slices, low-dose expiratory phase) using multi-slice spiral CT to capture ballooning and collapse in subsegmental bronchi.
Advanced techniques include dynamic free-breathing CT scans, coronal MinIP reconstructions for bronchiectasis extent, and 3D volume-rendered tracheobronchial tree for cartilage ring assessment.
Virtual bronchoscopy simulates endoscopy non-invasively, ideal pre-transplant; avoid biopsy due to risks—CT suffices for diagnosis after excluding mimics.
Pitfall: Ensure full inspiration/expiration; quantify collapse as (inspiratory – expiratory diameter)/inspiratory diameter x 100% for objective reporting.
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