Non-fibrotic hypersensitivity pneumonitis
A non-fibrotic hypersensitivity pneumonitis (plural: pneumonitides) is a pathological subgroup of hypersensitivity pneumonitis.
Radiographic features
CT
Often shows "diffusely distributed" :
- lung infiltrative ground-glass changes and
- mosaic attenuation: typically reflects coexistent lobules affected by pneumonitis (increased attenuation) interspersed with lobules of normal or slightly decreased attenuation (due to bronchiolar obstruction)
and
at least one HRCT abnormality suggestive of small airway disease which include :
- small (<5 mm) centrilobular nodules on inspiratory images
- air trapping on expiratory images
Additional HRCT features which are non-specific but can be compatible with non-fibrotic hypersensitivity pneumonitis in the appropriate clinical context :
- uniform and subtle ground glass changes
- airspace consolidation
- lung cysts
Differential diagnosis
Considerations on CT include
