Swyer–James syndrome

Overview

Swyer–James syndrome, also known as unilateral hyperlucent lung syndrome or Swyer–James–MacLeod syndrome, is a rare pulmonary disorder characterized by unilateral lung hypoplasia and air trapping. It results in one lung appearing smaller and more radiolucent (darker) on imaging due to decreased vascularity and alveolar destruction.

This syndrome is typically diagnosed in childhood or adulthood and is usually a sequela of childhood bronchiolitis obliterans caused by viral infections such as adenovirus. Swyer–James syndrome affects lung function and can cause recurrent respiratory infections and reduced exercise tolerance.

Causes

Swyer–James syndrome is most commonly caused by childhood respiratory infections leading to bronchiolitis obliterans, a condition where small airways become inflamed and scarred. The resulting airway obstruction and damage impair lung development and growth, causing:

• Destruction or underdevelopment of lung parenchyma on one side

• Reduced pulmonary blood flow and hypovascularity

• Air trapping due to bronchial obstruction

Other less common causes include congenital vascular abnormalities or trauma affecting lung development.

Symptoms

Symptoms of Swyer–James syndrome vary widely and may include:

• Recurrent respiratory infections, particularly affecting the hypoplastic lung

• Chronic cough

• Dyspnea (shortness of breath), especially on exertion

• Wheezing

• Reduced exercise tolerance

• In some cases, the syndrome may be asymptomatic and discovered incidentally on imaging

Diagnosis

Diagnosis is based on clinical features and characteristic imaging findings:

• Chest X-ray: Shows unilateral hyperlucent lung with decreased volume and reduced vascular markings.

• Computed tomography (CT) scan: Provides detailed visualization of air trapping, bronchial narrowing, and lung hypoplasia.

• Ventilation-perfusion (V/Q) scan: Demonstrates reduced perfusion in the affected lung.

• Pulmonary function tests: May reveal obstructive or restrictive patterns.

• Clinical history: Previous severe childhood respiratory infections support the diagnosis.

Treatment

There is no specific cure for Swyer–James syndrome, so treatment focuses on symptom management and prevention of complications:

• Prompt treatment of respiratory infections with antibiotics when necessary

• Bronchodilators and inhaled corticosteroids to manage airway obstruction and inflammation

• Chest physiotherapy and pulmonary rehabilitation to improve lung clearance and function

• Avoidance of smoking and environmental pollutants

• Regular monitoring with pulmonary function tests and imaging

• Surgical intervention is rarely needed but may be considered in severe localized disease

Prognosis

The prognosis of Swyer–James syndrome is generally good, especially with early recognition and appropriate management. Many patients maintain adequate lung function and lead normal lives with minimal symptoms.

However, recurrent infections and progressive lung damage can occur, particularly without treatment. Long-term follow-up is essential to monitor lung health and address complications promptly.