Idiopathic interstitial pneumonia - classification by the American Thoracic Society (ATS) and the European Respiratory Society (ERS)

This multidisciplinary concensus was adopted in 2001 by both the American Thoracic Society (ATS) and the European Respiratory Society (ERS) in order to standardize classification of the idiopathic interstitial pneumonias.

Name Interstitial pulmonary fibrosis Non-specific interstitial pneumonia Cryptogenic organising pneumonia Acute interstitial pneumonia Desquamative interstitial pneumonia Respiratory bronchiolitis - Interstitial lung disease Lymphoid interstitial pneumonia
Histological pattern UIP NSIP OP DAD DIP RB LIP
Radiographic features reticular pattern, basal ground-glass, reticular pattern patchy bilateral consolidation diffuse ground-glass and/or consolidation ground-glass bronchial wall thickening, ground-glass reticular opacity, nodules
Distribution on CT peripheral, subpleural, basal peripheral, subpleural, lower zone, basal subpleural, peribronchial diffuse lower zone, peripheral diffuse diffuse
CT findings reticular pattern, honeycombing, traction bronchiectasis, architectural distortion, focal ground-glass ground-glass, irregular reticular pattern patchy bilateral consolidation or nodules consolidation and ground-glass, often lobular sparing ground-glass, reticular lines bronchial wall thickening, centrilobular nodules, patchy ground glass centrilobular nodules, ground glass, septal and bronchovascular thickening, thin-walled cysts


1. American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias: This Joint Statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) was adopted by the ATS Board of Directors, June 2001 and by The ERS Executive Committee, June 2001. American Journal of Respiratory and Critical Care Medicine. 2002 Jan 15;165(2):277–304
2. Clinical Atlas of Interstitial Lung Disease. Springer; 2007.