Swyer-James Syndrome

A frontal chest radiograph of a 56-year-old man demonstrates a unilateral left hyperlucent lung with a normal lung volume.

An axial inspiratory and expiratory (not shown) chest CT shows evidence of air trapping of the left lung parenchyma, parts of the right lung and cystic bronchiectases. Note small pulmonary arteries in the areas of air trapping.

Facts: Swyer-James Syndrome

• Original description on x-ray: unilateral small lung with hyperlucency and air trapping
• Typically a result of viral respiratory infection in infancy or childhood (it is a post-infectious form of bronchiolitis obliterans)
• Diagnosis based on radiologic and clinical findings rather than pathologic examination. If pathologic examination is performed, there are bronchiolitis obliterans with various degrees of chronic inflammation, fibrosis and dilatation of airways and air spaces distal to the obstructed bronchioles.
• Clinicians need to exclude other causes of air trapping such as obstructing tumor or foreign body

Imaging

• X-ray: unilateral hyperlucent lung, or bilateral asymmetric hyperlucency of the lungs. Lung volumes are usually decreased on the site of lucency, but can be normal or increased
• CT: air trapping usually more extensive than on x-ray, and usually bilateral. May or may not have bronchiectasis
• It is important to look for causes of air trapping on CT such as obstructing tumor or foreign body, as it may obviate the need for bronchoscopy

Reference:

Moore ADA, Godwin JD, Dietrich PA, et al. Swyer-James syndrome: CT findings in eight patients. AJR 1992; 158:1211-1215.