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)”.

Combined pulmonary fibrosis and emphysema (CPFE) is a syndrome of combined emphysema of the upper lobes and fibrosis of the lower lobes defined on chest computed tomography, and characterised by subnormal spirometry, severe impairment of gas exchange, high prevalence of pulmonary hypertension, and poor survival. Characteristic functional profile of CPEF is strongly impaired carbon monoxide diffusing capacity of the lung, and hypoxaemia at exercise, with preserved lung volumes. Despite subnormal spirometry, which may be responsible for its under recognition, CPFE is a severe entity. The presence of pulmonary arterial hypertension at diagnosis is a critical determinant of prognosis.