[Idiopathic diffuse interstitial lung disease].

The interstitial pneumonias are characterized by inflammatory and fibrosing lesions of the lung interstitium. Idiopathic interstitial pneumonias are now classified into four main clinicopathologic entities. Idiopathic pulmonary fibrosis has a chronic course with a poor response to therapy, and corresponds to the characteristic histopathologic lesions of usual interstitial pneumonia. Acute interstitial pneumonia, fulminant, is seen in young patients. Desquamative (alveolar macrophage) interstitial pneumonia, related to tobacco smoking, has a good prognosis. Recently individualized from usual interstitial pneumonia, nonspecific interstitial pneumonia has a better prognosis than idiopathic pulmonary fibrosis. This classification has both diagnostic and prognostic implications.