Abstract
Idiopathic interstitial pneumonias comprise a heterogenous group of acute and chronic respiratory conditions. Katzenstein and Myers (1) classified these disorders according to several pathologically distinct categories: usual interstitial pneumonitis (UIP), desquamative interstitial pneumonitis ? respiratory bronchiolitis interstitial lung disease, acute interstitial pneumonitis, nonspecific interstitial pneumonitis and cryptogenic organizing pneumonitis or bronchiolitis obliterans organizing pneumonia (1). These disorders present with similar clinical features of shortness of breath, diffuse pulmonary infiltrates on chest radiograph, and histologically, a varying combination of inflammation and fibrosis. However, the natural history and response to therapy differs substantially, as some categories have more favourable prognoses than others (2). Idiopathic pulmonary fibrosis (IPF) or fibrosing alveolitis is the clinical terminology for a specific interstitial pneumonia for which the pathological process is UIP. A disorder of unknown etiology, IPF is the most common and most lethal of all interstitial pneumonias.