Disease/Syndrome

Hypersensitivity pneumonitis, acute

Category

Acute Poisoning

Acute/Chronic

Acute-Moderate

Synonyms

HP; Extrinsic allergic alveolitis; Farmer' lung; Bird-breeder's lung; Wood trimmer's disease; Maple bark-stripper's lung; Metalworking fluids HP

Biomedical References

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Comments

Acute presentation: flu-like illness with cough; Subacute: recurrent "pneumonia"; Chronic: exertional dyspnea, productive cough, and weight loss; Most patients have abnormal imaging studies (chest x-ray or high-resolution CT). Crepitant rales are heard in some cases. Pulmonary function testing shows a restrictive defect in early disease and a restrictive, obstructive or mixed defect in late disease. Precipitating antibodies are neither sensitive nor specific, and their presence is no longer considered a hallmark of HP. Some patients have decreased diffusion capacity and arterial hypoxemia. If the diagnosis is in doubt, bronchoalveolar lavage (BAL) typically shows lymphocytosis. Surgical lung biopsy may be indicated if bronchoscopy is nondiagnostic. The disease latency varies from a few weeks to years after first exposure. Symptoms appear or worsen within a few hours of antigen exposure to bioaerosols of microbial or animal antigens or rarely to a few reactive chemicals. Complete recovery usually occurs if exposure is terminated early. Otherwise, the disease may progress to interstitial fibrosis. [Murray, p. 1783-1799]

Latency/Incubation

Weeks to years until "sensitized"; acute symptoms 4-12 hours after exposure;

Diagnostic

Clinical; Chest x-ray; HRCT; Pulmonary function testing; BAL; Lung biopsy;

ICD-9 Code

495.9

Related Information in Haz-Map
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Agents

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