Classification of Interstitial Lung Disease

IdIopAthIc InterstItIAl pneumonIAs The terminology of idiopathic interstitial pneumonias (IIP) varies from country to country and is often confusing. It is called idiopathic pulmonary fibrosis (IPF) in the United States,7 cryptogenic fibrosing alveolitis (CFA) in the United Kingdom8 or idiopathic interstitial pneumonia in Japan.9 In our country, it is termed either as IPF or CFA. The landmark classification of chronic interstitial pneumonia was proposed by Leibow and Carrington in 1969.10 They described five types of chronic interstitial pneumonias: (i) usual interstitial pneumonia (UIP), (ii) bronchiolitis obliterans with interstitial pneumonia (BIP), (iii) desquamative interstitial pneumonia (DIP), (iv) lymphoid interstitial pneumonia (LIP) and (v) giant cell interstitial pneumonia (GIP). Subsequently, Katzenstein11 and Muller and Colby12 provided classifications that retained UIP and DIP as distinct entities and added new entities such as respiratory bronchiolitis associated interstitial lung disease (RB– ILD), bronchiolitis obliterance organizing pneumonia (BOOP), acute interstitial pneumonia (AIP), and non-specific interstitial pneumonia (NSIP). The terms GIP and LIP were omitted from their classifications because GIP was found to be associated with hard metal pneumoconiosis and LIP was found to develop into