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Hypersensitivity pneumonitis

  • Alternative Names

    Extrinsic allergic alveolitis; Farmer's lung; Mushroom picker's disease; Humidifier or air-conditioner lung; Bird breeder's or bird fancier's lung


    Symptoms of acute hypersensitivity pneumonitis may occur 4 - 6 hours after you have left the area where the foreign substance is found, making it difficult to find a connection between your activity and the disease.

    Symptoms may include:

    • Chills
    • Cough
    • Fever
    • Malaise (feeling ill)
    • Shortness of breath

    Symptoms of chronic hypersensitivity pneumonitis may include:

    • Breathlessness, especially with activity
    • Cough, often dry
    • Loss of appetite
    • Unintentional weight loss

    Signs and tests

    Your doctor may hear abnormal lung sounds called crackles (rales) when listening to your chest with a stethoscope.

    Lung changes due to chronic hypersensitivity pneumonitis may be seen on a chest x-ray. Other tests may include:

    • Aspergillus precipitins test
    • Bronchoscopy with washings, biopsy, and bronchoalveolar lavage
    • CBC
    • High-resolution CT scan of the chest
    • Hypersensitivity pneumonitis antibody panels
    • Krebs von den Lungen-6 assay (KL-6)
    • Pulmonary function tests
    • Video-assisted or open-lung biopsy