Interstitial lung disease is the term for a collection of more than 100 lung conditions that bear similar clinical characteristics, including lung tissue inflammation and scarring, according to ClevelandClinic.com. While some examples of interstitial lung disease are associated with other underlying medical conditions or exposure to certain drugs and environmental hazards, others are categorized as idiopathic--having no known cause.
Idiopathic Interstitial Lung Diseases
Idiopathic interstitial lung diseases are those that have no clear underlying cause. According to Merck.com, the most common of these conditions is idiopathic pulmonary fibrosis. There are five additional idiopathic subtypes, including nonspecific interstitial pneumonia, cryptogenic organizing pneumonia--sometimes referred to as bronchiolitis obliterans organizing pneumonia, or BOOP--respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia and acute interstitial pneumonia. Though superficially they share similar clinical features, each of these types causes varying degrees of lung tissue inflammation and scarring. According to National Jewish Health, when two or more first- or second-degree family members develop one of these idiopathic interstitial lung diseases, doctors refer to the condition as familial pulmonary fibrosis.
Drug-Associated Interstitial Lung Disease
Drug-associated interstitial lung disease develops as a result of exposure to prescription and/or illicit drugs. For example, antibiotics such as sulfasalazine and nitrofurantoin, chemotherapy drugs such as zinostatin and carmustine, the antiarrhythmic heart medication amiodarone, drugs used to treat auto-immune diseases--including methotrexate, infliximab and etanercept--anti-inflammatory medications such as aspirin and illicit drugs like heroin can all lead to drug-associated interstitial lung disease, according to ClevelandClinic.com.
Occupational Exposure-Related Interstitial Lung Disease
Occupational exposure-related interstitial lung disease develops among those who inhale harmful substances such as asbestos and silica particles while on the job, according to ClevelandClinic.com. For example, coal worker's pneumoconiosis forms among workers who repeatedly breathe in coal dust, carbon or graphite particles while working in a mine.
Connective Tissue Disease-Associated Interstitial Lung Disease
Connective tissue disease-associated interstitial lung disease occurs among those with health conditions that affect the fibrous material that supports and holds together structures throughout the body. According to the UCSF Medical Center, examples include rheumatoid arthritis-related interstitial lung disease, scleroderma-related interstitial lung disease and systemic lupus erythematosis-related interstitial lung disease. Individuals with myositis--systemic inflammation of the skeletal muscles--and Sjogren's syndrome--an autoimmune condition causing dry eyes and mouth and arthritis--may also develop lung inflammation and fibrosis associated with interstitial lung disease.
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis is an example of interstitial lung disease caused by repeated exposure to certain antigens--substances that cause the immune system to respond by producing antibodies. This condition can develop when individuals inhale substances such as bacteria, fungi and animal proteins. For example, those who work closely with birds may develop "bird fancier's lung," while farmers exposed to moldy hay may develop "farmer's lung," according to ClevelandClinic.com. Once sensitized through a single exposure, individuals are vulnerable to developing acute hypersensitivity pneumonitis--sudden onset of flu-like symptoms, chest pain and shortness of breath--upon re-exposure. Those who repeatedly inhale small amounts of these antigens over time are susceptible to developing chronic hypersensitivity pneumonitis--a form of the condition that often causes no obvious symptoms for years.
