“ Also known as extrinsic allergic alveolitis, it is a granulomatous response to an inhaled antigen. The antigens involved include animal pr...
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Also known as extrinsic allergic alveolitis, it is a granulomatous response to an inhaled antigen. The antigens involved include animal proteins (e.g. bird fancier’s lung), microbes (e.g. farmer’s lung, hot tub lung, etc.), chemicals, etc. Presentation may be acute (e.g. 6-8 hours after exposure) or chronic after years of exposure.
occurs in non-atopic patients as a response to organic dusts
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• A normal chest radiograph is the most common finding.
• Look for multiple poorly defined small opacities, patchy/diffuse airspace shadowing.
• Pleural effusions are unusual.
• In chronic cases, there may be fibrosis, typically in the upper zones.
• Septal lines are seen in acute extrinsic allergic alveolitis
• Patchy ground-glass change and small ill-defined centrilobular nodules.
• Look for air-trapping giving a mosaic pattern of attenuation (i.e. trapped air in secondary lobules).
Is a cause of upper lobe fibrosis
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