The etiology of idiopathic pulmonary fibrosis (IPF) remains incompletely understood. Historically, IPF was thought to be a condition characterized by inflammation, leading to fibrosis. The current understanding is based on the concept of repetitive injury with an abnormal wound healing response in a genetically susceptible host [1]. The initial injury appears to be to the alveolar epithelial cells (AECs), particularly type II AECs. The current understanding of the pathogenesis of IPF is depicted in Fig. 4.1.
