Exogenous allergic alveolitis

Exogenous allergic alveolitis (EAA), also known as hypersensitivity pneumonitis (HP), is an immune-mediated lung disease caused by repeated inhalation of organic dust or chemically active substances. The main clinical manifestations are fever, cough, dyspnea, hypoxemia and sore muscles and joints. The basic histopathological changes are diffuse mononuclear cell infiltration in early interstitial lung, alveoli, and terminal bronchiole. Granuloma often develops later and can develop into pulmonary fibrosis in the later stages. The disease was first reported by Campbell in 1932.