Chronic hypersensitivity pneumonitis

Chronic hypersensitivity pneumonitis (CHP) refers to hypersensitivity pneumonitis where there is radiological evidence of fibrosis and represents the end-stage of repeated or persistent pneumonitis 7.

High-resolution CT of the chest typically reveals indistinct centrilobular peribronchiolar nodular opacities of varying numbers 5. Other features include:

There is often a middle or upper zone predominance of CT findings with sparing of the lung bases, unlike non-specific interstitial pneumonia (NSIP) or usual interstitial pneumonia (UIP), which show a lower zone predominance.

The presence of an extensive reticular pattern, traction bronchiectasis, and honeycombing have been shown to closely correlate with the presence of histologic fibrosis in chronic hypersensitivity pneumonitis 6.

The presence of fibrotic changes confers a poor prognosis.

In some cases, it may be difficult to differentiate from idiopathic pulmonary fibrosis 4.

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Article information

rID: 17191
System: Chest
Tag: cases
Synonyms or Alternate Spellings:
  • Chronic hypersensitivity pneumonitis (CHP)
  • Chronic HP
  • Chronic EAA
  • Chronic extrinsic allergic alveolitis
  • Chronic extrinsic allergic alveolitis (EAA)

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