Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common of the interstitial pneumonias of unknown etiology and the most aggressive interstitial lung disease. IPF is confirmed by the identification of usual interstitial pneumonia (UIP) on surgical lung biopsy (1–5). The idiopathic interstitial pneumonias (IIPs) are a group of diffuse parenchymal lung diseases (DPLDs) also described as interstitial lung diseases. The IIPs are a heterogeneous group of nonneoplastic disorders resulting from damage to the lung parenchyma by varying patterns of inflammation and fibrosis (1). The IIPs include the entities of IPF, nonspecific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP), acute interstitial pneumonia (AIP), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), desquamative interstitial pneumonia (DIP), and lymphocytic interstitial pneumonia (LIP). It is important to emphasize that IPF is a progressive and irreversible illness and, until now, there has been no available drug that has been able to modify the progressive natural course of IPF and its usual terminal outcome (1, 2, 6). It is characterized by radiographically evident interstitial infiltrates predominantly affecting the lung bases and by progressive dyspnea and worsening of pulmonary function, pathologically by fibroblast proliferation and extracellular matrix accumulation resulting in irreversible distortion of the architecture of the lung (1). The current strict definition of IPF provides a new focus for basic and clinical research that will improve insight into the pathogenesis of this disorder and stimulate the development of novel therapies (7). Definition