title: Respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia: different entities or part of the spectrum of the same disease process?
abstract: OBJECTIVE
  Our objective was to assess high-resolution CT findings of respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia and to determine whether these three entities could be reliably differentiated by radiologic criteria.
  
  
  METHODS
  CT scans (1- to 3-mm collimation) were reviewed in 40 patients with pathologically proven respiratory bronchiolitis (n = 16), respiratory bronchiolitis-associated interstitial lung disease (n = 8), or desquamative interstitial pneumonia (n = 16). All patients with respiratory bronchiolitis and respiratory bronchiolitis-associated interstitial lung disease were cigarette smokers, and 85% of the patients with desquamative interstitial pneumonia had a history of smoking. CT scans were independently reviewed by two radiologists who assessed the pattern and distribution of abnormalities.
  
  
  RESULTS
  The predominant abnormalities in respiratory bronchiolitis were centrilobular nodules (12 [75%] of 16 patients) and ground-glass attenuation (six [38%] of 16). No single abnormality predominated in the respiratory bronchiolitis-associated interstitial lung disease group; findings included ground-glass attenuation (four [50%] of eight), centrilobular nodules (three [38%] of eight), and mild fibrosis (two [25%] of eight). All patients with desquamative interstitial pneumonia showed ground-glass attenuation, and 10 (63%) of the 16 showed evidence of fibrosis.
  
  
  CONCLUSIONS
  The significant overlap between the CT findings of respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia is consistent with the concept that they represent different degrees of severity of small airway and parenchymal reaction to cigarette smoke.
authors.affiliation: Department of Radiology, Vancouver Hospital and Health Sciences Centre, University of British Columbia, Canada.
authors.forename: L E
authors.initials: LE
authors.lastname: Heyneman
authors.forename: S
authors.initials: S
authors.lastname: Ward
authors.forename: D A
authors.initials: DA
authors.lastname: Lynch
authors.forename: M
authors.initials: M
authors.lastname: Remy-Jardin
authors.forename: T
authors.initials: T
authors.lastname: Johkoh
authors.forename: N L
authors.initials: NL
authors.lastname: Müller
mesh_terms: D000328:Adult; D000368:Aged; D001988:Bronchiolitis / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects; D014057:Tomography, X-Ray Computed