Chronic interstitial lung disease is an uncommon clinical entity in childhood. The onset is frequently insidious with progressive tachypnea, dyspnea, cyanosis, clubbing, weight loss, and hypoxia. More than 100 different occupational and environmental agents have been identified as causes, although two thirds of cases are reported as idiopathic.1 Assessment can involve invasive procedures such as bronchoalveolar lavage and open lung biopsy. Treatment of the idiopathic forms includes use of corticostenoids and cytotoxic agents, and response is variable with progression to pulmonary fibrosis being a common end stage. In contrast to this grim prognosis, the similar clinical pattern associated with hypersensitivity pneumonitis, also identified as "extrinsic allergic alveolitis," can be rapidly reversed if the offending antigen is identified and eliminated.
Quantitative assessment of specific serum IgGs may verify source of environmental exposure in extrinsic allergic alveolitis (EAA)
