Idiopathic pulmonary fibrosis (IPF) is a specific type of interstitial pneumonia with chronic progressive fibrosis of unknown etiology. The lesions are limited to the lungs and are more common in the elderly. Extensive fibrosis of the pulmonary interstitium leads to thickening of the lung tissue, resulting in an irreversible loss of the ability of the lung tissue to exchange oxygen. It is a fatal respiratory disease.