Idiopathic pulmonary fibrosis | NSIP | Respiratory bronchiolitis-associated ILD | DIP | LIP | Cryptogenic organising pneumonia | Acute interstitial pneumonia | |
Histological lesion | UIP | NSIP | Respiratory bronchiolitis ILD | DIP | LIP | Organising pneumonia | Diffuse alveolar damage |
Key histological features | Patchy subpleural fibrosis with temporal and spatial heterogeneity; fibroblastic foci are typically observed at the leading edge of fibrosis | Temporally homogeneous interstitial fibrosis, often with associated mild-to-moderate interstitial infiltrate | Patchy bronchiolocentric distribution of mild fibrosis, submucosal lymphocytic infiltrate and pigmented macrophages within alveolar ducts | Diffuse macrophage accumulation in distal airspaces with accompanying alveolar septal thickening and inflammation | Dense interstitial lymphoid infiltrate, type II cell hyperplasia and occasional lymphoid follicles | Organising intraluminal fibrosis with patchy but temporally uniform distribution; underlying lung architecture preserved | Temporally uniform lesion with alveolar septal thickening, airspace filling and hyaline membranes; later organisation and fibrosis |
Mean age of onset yrs | 65 | 50–55 | 40–50 | 40–50 | 40–50 | 55 | 50 |
Rate of onset | Insidious | Insidious | Insidious | Insidious | Insidious | Subacute | Acute |
Prognosis | Poor | Intermediate | Good | Good | Intermediate | Good | Very poor |
NSIP: nonspecific interstitial pneumonia; ILD: Interstitial lung disease; DIP: desquamative interstitial pneumonia; LIP: lymphocytic interstitial pneumonia; UIP: usual interstitial pneumonia.