Pneumonitele interstiţiale idiopatice (PII) reprezintă un grup de afecţiuni arenchimatoase pulmonare (subgrup al pneumopatiilor interstiţiale difuze) cu multe trăsături comune, dar suficient de distincte pentru a fi acceptate ca şi entităţi aparte. PII pot fi deosebite de alte forme ale pneumopatiilor interstiţiale difuze in baza tabloului clinic, modificărilor de laborator, pattern-urilor imagistice şi morfologice. Pattern-ul radiologic al PII, poate fi similar sau identic cu cel al leziunilor pulmonare din alte boli, cum ar fi colagenozele, pneumonitele prin hipersensibilizare, azbestoza şi intoxicaţiile medicamentoase.

The idiopathic interstitial pneumonias (IIPs) are a group of diffuse parenchymal lung diseases that share many features but are sufficiently different from one another to be designated as separate disease entities. IIPs can be easily distinguished from other forms of diffuse parenchymal lung disease by clinical methods, including history, physical examination, laboratory studies, imaging, and pathologic analysis. Radiological patterns seen in the IIPs are similar or identical to those founded in many other conditions, including collagen vascular disease, drug reactions, asbestosis, and chronic hypersensitivity pneumonitis.