Updated Imaging Classification of Hypersensitivity Pneumonitis

Radiol Clin North Am. 2022 Nov;60(6):901-913. doi: 10.1016/j.rcl.2022.06.013. Epub 2022 Sep 7.


Hypersensitivity pneumonia (HP) refers to a heterogeneous group of interstitial lung diseases resulting from a non-IgE immune-mediated reaction to inhaled pathogens in susceptible and sensitized hosts. Environmental and genetic factors are important substrates of disease pathogenesis. A recurrent or ongoing airborne exposure results in activation of humoral and cellular immune responses. This article discusses key clinical, radiologic, and histopathologic features of HP and reviews current recommendations.

Keywords: Fibrotic hypersensitivity pneumonitis; high-resolution CT; histopathology; interstitial lung disease; non-fibrotic hypersensitivity pneumonitis.

Publication types

  • Review

MeSH terms

  • Alveolitis, Extrinsic Allergic* / diagnostic imaging
  • Diagnostic Imaging
  • Humans
  • Lung / diagnostic imaging
  • Lung / pathology
  • Lung Diseases, Interstitial*