Early diagnosis of parenchymal lung diseases is now possible. Reduced risk of fibrosis and irreversibly reduced lung function

: Although parenchymal, or interstitial lung diseases constitute a heterogeneous category, a common feature is the occurrence of an alveolar and interstitial inflammatory reaction. The alveolitis may regress, but may also heal with scarring and fibrosis, resulting in chronic impairment of lung function. Early diagnosis is important in order to identify patients at risk of lung function impairment. Diagnosis has been facilitated by the advent of sophisticated, particularly radiological and bronchoscopic methods in recent years, thus enabling intervention at an earlier stage in the disease course. The various diagnostic alternatives available for the investigation of parenchymal lung diseases are reviewed in the article.