pathology
Last reviewed 01/2018
Allergic extrinsic alveolitis is a hypersensitivity reaction affecting the lung parenchyma occurring in response to inhaled inorganic dusts.
The pathogenesis is thought to be different in acute and chronic cases:
- acute:
- usually the result of a type III - immune complex - hypersensitivity reaction
- precipitins can be demonstrated in the serum
- chronic:
- principally a type IV (cell-mediated) hypersensitivity reaction, characterised by:
- lymphocyte infiltration
- giant cells
- granulomata
- diffuse lung fibrosis
- endobronchial exudates
- bronchiolitis obliterans