"Fibrosis" is a term used to refer to scarring, so pulmonary fibrosis means scarring in the lungs. Pulmonary fibrosis can be caused by many conditions, including chronic inflammatory processes (sarcoidosis, Wegener's granulomatosis), infections, environmental agents (asbestos, silica, exposure to certain gases), exposure to ionizing radiation (such as radiation therapy to treat tumors of the chest), chronic conditions (lupus, rheumatoid arthritis), and certain medications, such as nitrofurantoin and methotrexate.

 

In a condition known as hypersensitivity pneumonitis, fibrosis of the lungs can develop following a heightened immune reaction to inhaled organic dusts or occupational chemicals. This condition most often results from inhaling dust contaminated with bacterial, fungal, or animal products. Examples include silo fillers disease and pigeon breeders lung disease.

 

In some people, in fact in most cases, chronic pulmonary inflammation and fibrosis develop without an identifiable cause. Most of these people have a condition called idiopathic pulmonary fibrosis (IPF) that does not respond to medical therapy, while some of the other types of fibrosis, such as nonspecific interstitial pneumonitis (NSIP), may respond to immune suppressive therapy.

 

Other names for various types of pulmonary fibrosis that have been used in the past include chronic interstitial pneumonitis, Hamman-Rich Syndrome, usual interstitial pneumonitis (UIP) and diffuse fibrosing alveolitis. WebMD