ICD-11

The idiopathic interstitial pneumonias (pneumonitises) are a subset of diffuse interstitial lung diseases of unknown etiology characterised by expansion of the interstitial compartment (i.e. that portion of the lung parenchyma sandwiched between the epithelial and endothelial basement membranes) with an infiltrate of inflammatory cells. The inflammatory infiltrate is sometimes accompanied by fibrosis, either in the form of abnormal collagen deposition or proliferation of fibroblasts capable of collagen synthesis.

The idiopathic interstitial pneumonias (pneumonitises) are a subset of diffuse interstitial lung diseases of unknown etiology characterized by expansion of the interstitial compartment (ie, that portion of the lung parenchyma sandwiched between the epithelial and endothelial basement membranes) with an infiltrate of inflammatory cells. The inflammatory infiltrate is sometimes accompanied by fibrosis, either in the form of abnormal collagen deposition or proliferation of fibroblasts capable of collagen synthesis.

The IIPs include the entities of six “Major idiopathic interstitial pneumonias (pneumonitises)” (Idiopathic pulmonary fibrosis, Idiopathic nonspecific interstitial pneumonia (pneumonitis), Respiratory bronchiolitis–interstitial lung disease, Desquamative interstitial pneumonia (pneumonitis), Cryptogenic organizing pneumonia (pneumonitis), Acute interstitial pneumonia (pneumonitis), two “Rare idiopathic interstitial pneumonia (pneumonitis)” (Idiopathic lymphoid interstitial pneumonia (pneumonitis), Idiopathic pleuroparenchymal fibroelastosis) and “Unclassifiable idiopathic interstitial pneumonias (pneumonitises)”.

Idiopathic pulmonary fibrosis (IPF) is defined as a specific form of chronic, progressive fibrosing interstitial pneumonia (pneumonitis) of unknown cause, occurring primarily in older adults, limited to the lungs, and associated with the histopathologic and/or radiologic pattern of UIP (Usual Interstitial Pneumonia). The definition of IPF requires the exclusion of other forms of interstitial pneumonia (pneumonitis) including other idiopathic interstitial pneumonias (pneumonitis) and Interstitial Lung Disease (ILD) associated with environmental exposure, medication, or systemic disease.