TY - CHAP M1 - Book, Section TI - Hypersensitivity Pneumonitis A1 - Gifford, Alex H. A1 - Enelow, Richard I. A2 - Grippi, Michael A. A2 - Elias, Jack A. A2 - Fishman, Jay A. A2 - Kotloff, Robert M. A2 - Pack, Allan I. A2 - Senior, Robert M. A2 - Siegel, Mark D. PY - 2015 T2 - Fishman's Pulmonary Diseases and Disorders, 5e AB - Hypersensitivity pneumonitis (HP), or extrinsic allergic alveolitis, is a spectrum of interstitial, alveolar, and bronchiolar lung diseases resulting from immunologically induced inflammation in response to inhalation of a wide variety of different materials that are usually organic or low–molecular-weight chemical antigens (or haptens), which may lead to irreversible lung damage. Despite the terms hypersensitivity and allergic, HP is not an atopic disease and is not associated with increased IgE or eosinophils. The prevalence of HP is quite variable in different populations, presumably because of differing intensity, frequency, and duration of inhalation exposure, and also probably due to host factors that have yet to be identified. Once thought to be a relatively rare disease, it is becoming more frequently recognized as awareness is of the limitations of classical diagnostic criteria has increased. Among pigeon breeders, 8% to 30% of members of pigeon-breeding clubs who participated in surveys exhibited evidence of HP, so-called pigeon breeder’s disease (Fig. 58-1). Among farmers, 0.5% to 5% have symptoms compatible with HP, so-called farmer’s lung disease. The prevalence of symptoms is lower in farms that use hay-drying methods that decrease exposure to the responsible antigens and increased after a wet summer season. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accessmedicine.mhmedical.com/content.aspx?aid=1122360968 ER -