Hypersensitivity Pneumonitis: An Updated Diagnostic Guide for Internists

Med Clin North Am. 2022 Nov;106(6):1055-1065. doi: 10.1016/j.mcna.2022.08.007. Epub 2022 Oct 4.


This summary highlights updated definitions, terminology, and classification systems proposed in the diagnosis of hypersensitivity pneumonitis. Clinical presentation, epidemiology, and pathophysiology are reviewed from the most recent data. Radiographic and histopathologic diagnostic criteria are presented in a manner relevant to the practice of general medicine internists, including new guideline recommendations. The role of adjunctive tests, such as serum IgG testing, bronchoalveolar lavage lymphocyte analysis, and pulmonary function testing is discussed in the context of supporting diagnostic confidence for hypersensitivity pneumonitis diagnosis. Finally, new diagnostic algorithms are synthesized and applied to the general internal medicine setting.

Keywords: Hypersensitivity pneumonitis; Interstitial lung disease; Pulmonary fibrosis.

Publication types

  • Review

MeSH terms

  • Alveolitis, Extrinsic Allergic* / diagnosis
  • Alveolitis, Extrinsic Allergic* / pathology
  • Bronchoalveolar Lavage
  • Humans
  • Immunoglobulin G
  • Respiratory Function Tests


  • Immunoglobulin G