Hypersensitivity Pneumonitis

HYPERSENSITIVITY PNEUMONITIS

Hypersensitivity pneumonitis, also called extrinsic allergic alveolitis, is an inflammatory condition of the lung caused by the inhalation of small organic or, less commonly, inorganic particles in susceptible individuals. Some thirty different varieties of the condition have been described, the most common of which is known as "farmer's lung." Hypersensitivity pneumonitis represents an important category of occupational lung disease. The inhaled particles are usually fungal spores or bacteria that are found in moldy or rotting material, including hay, compost, bark, wood dust, and grains. Hypersensitivity pneumonitis affects the tissue of the lung where gas exchange occurs and is distinguished from bronchial asthma, which affects the lungs' airways. The condition may be acute or chronic. Treatment consists of avoiding exposure and, in severe cases, the administration of corticosteroid drugs.

JOHN L. STAUFFER

(SEE ALSO: Asthma; Occupational Lung Disease)

BIBLIOGRAPHY

Murphy, D. M. F.; Morgan, W. K. C.; and Seaton, A. (1995). "Hypersensitivity Pneumonitis." In Occupational Lung Diseases, 3rd edition, eds. W. K. C. Morgan and A. Seaton. Philadelphia, PA: W. B. Saunders.