Classification of interstitial pneumonias: ready for the future or stuck in the past?

Interstitial lung diseases (ILDs) or interstitial pneumonias (IPs) are a large group of rare diffuse lung diseases that primarily affect the interstitial space, alveoli and, to a lesser extent, the small airways and pulmonary vasculature. The classification and grouping of diseases in “boxes” has been an important element of medicine for decades, if not centuries. Disease classification aims at better describing disease entities, providing details for making a proper diagnosis and developing the rationale for disease-specific management. Good classifications, therefore, serve both clinical care and clinical research.