Swyer-James syndrome (SJS), also known as Swyer-James-MacLeod syndrome and Bret syndrome, is a rare lung condition that manifests as unilateral hemithorax lucency as a result of postinfectious obliterative bronchiolitis.
The condition typically follows a viral respiratory infection such as adenoviruses or Mycoplasma pneumoniae infection in infancy or early childhood 2-6.
It is generally characterised on radiographs by a unilateral small lung with hyperlucency and air trapping on expiration 2.
CT shows the affected lung as being hyperlucent with diminished vascularity. Disease can be unilateral or bilateral. The entire lung can be affected, however, there can also be lobar, segmental, and subsegmental involvement in a patchy distribution2. The size of the majority of the affected lobes is smaller, although occasionally they can be of normal size 3. There is usually no anteroposterior gradient attenuation 4. Bronchiectasis may be present, although this is not a universal finding 5.
MR angiography (MRA) may show a small pulmonary artery with diminished vascularity in the periphery 8.
Quantitative ventilation/perfusion lung scan shows a photopenic area in the affected aspect.
History and etymology
The condition was first described in Canada in the 1950s by:
- Paul Robert Swyer: English paediatrician in Canada
- William Mathieson MacLeod: English pulmonologist (1917-1977)
- George C W James: Canadian radiologist
It has also been referred to as MacLeod syndrome, but this is not advised given the presence of a rare genetic malformation bearing a similar name: McLeod syndrome. It was also described by J Bret in France, hence reference to the same condition as Janus syndrome and Bret syndrome.
Possible imaging differential considerations include:
- congenital lobar overinflation, though the lucent lung in this case is usually larger
- unilateral absence/proximal interruption of the main pulmonary artery
- hypogenetic lung syndrome (Scimitar syndrome)
One should also consider other causes of a unilateral hypertranslucent hemithorax.
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- 8.Yakut, Zeynep İlerisoy, et al. "Pulmonary MR Angiography in Swyer-James Syndrome." (2010).