idiopathic interstitial pneumonia idiopathic interstitial pneumonia idiopathic interstitial pneumonia (iip), or noninfectious pneumonia 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. idiopathic interstitial pneumoniaother namesnoninfectious pneumoniamicrograph of usual interstitial pneumonia (uip). uip is the most common pattern of idiopathic interstitial pneumonia and usually represents idiopathic pulmonary fibrosis. h&e stain. autopsy specimen.specialtyrespirology diagnosis classification can be complex, and the combined efforts of clinicians, radiologists, and pathologists can help in the generation of a more specific diagnosis. idiopathic interstitial pneumonia can be subclassified based on histologic appearance into the following patterns: histology clinical correlates desquamative interstitial pneumonia (dip) dip diffuse alveolar damage (dad) ards, aip, trali nonspecific interstitial pneumonia (nsip) nsip respiratory bronchiolitis 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. development table 1: development of the (histologic) idiopathic interstitial pneumonia classification leibow et al. (1969)katzenstein (1998)ats/ers (2002) uipuip uipdaddad nsipnsip dipdip/rbdip rb bipopop lip(lpd)lip gip(hmf)(hmf) uip=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.