DefinitionIdiopathic pulmonary fibrosis is scarring or thickening of the lungs without a known cause.Alternative NamesIdiopathic diffuse interstitial pulmonary fibrosis; IPF; Pulmonary fibrosis; Cryptogenic fibrosing alveolitis; CFA; Fibrosing alveolitis; Usual interstitial pneumonitis; UIPCauses, incidence, and risk factorsNo one knows what causes pulmonary fibrosis or why some people get it. It causes the lungs to become scarred and stiffened. This stiffening may make it increasingly difficult to breathe. In some people the disease gets worse quickly (over months to a few years), but other people have little worsening of the disease over time.The condition is believed to result from an inflammatory response to an unknown substance. "Idiopathic" means no cause can be found. The disease oc