| Idiopathic interstitial pneumonia | |
| Synonyms: | Noninfectious pneumonia |
| Field: | Respirology |
Idiopathic interstitial pneumonia (IIP), or noninfectious pneumonia[1] are a class of diffuse lung diseases. These diseases typically affect the pulmonary interstitium, although some also have a component affecting the airways (for instance, cryptogenic organizing pneumonitis). There are seven recognized distinct subtypes of IIP.[2]
Classification can be complex,[3] and the combined efforts of clinicians, radiologists, and pathologists can help in the generation of a more specific diagnosis.[4] [5]
Idiopathic interstitial pneumonia can be subclassified based on histologic appearance into the following patterns:[6] [7]
| Histology | Clinical Correlates | |
|---|---|---|
| Desquamative interstitial pneumonia (DIP) | DIP | |
| Diffuse alveolar damage (DAD) | ARDS, AIP, TRALI | |
| Nonspecific interstitial pneumonia (NSIP) | NSIP | |
| RB-ILD | ||
| Usual interstitial pneumonia (UIP) | CVD, IPF, drug toxicity, pneumoconiosis | |
| Organizing pneumonia | Cryptogenic organizing pneumonia | |
| Lymphoid interstitial pneumonia (LIP) | LIP |
Usual interstitial pneumonia is the most common type.[8]
Table 1: Development of the (histologic) idiopathic interstitial pneumonia classificationUIP=usual interstitial pneumonia; DAD=diffuse alveolar damage; NSIP=non-specific interstitial pneumonia; DIP=desquamative interstitial pneumonia; RB=respiratory bronchiolitis; BIP=bronchiolitis obliterans interstitial pneumonia; OP=organizing pneumonia; LIP=lymphoid interstitial pneumonia; LPD=lymphoproliferative disease (not considered a diffuse lung disease); GIP=giant cell interstitial pneumonia; HMF=heavy metal fibrosis, no longer grouped with diffuse lung disease
Lymphoid interstitial pneumonia was originally included in this category, then excluded, then included again.[9]