Hypersensitivity pneumonitis

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Hypersensitivity_pneumonitis, abbreviated HP, is a diffuse lung diseases caused by an allergen.

Hypersensitivity pneumonitis
Diagnosis in short

Synonyms extrinsic allergic alveolitis

LM centrilobular prominence of lesions, granulomata, chronic interstitial inflammation consisting primarily of lymphocytes, interstitial fibrosis, air space involvement (alveolitis)
LM DDx usual interstitial pneumonia, asbestosis
Site lung - see diffuse lung diseases

Clinical history allergen exposure
Prevalence uncommon
Radiology upper lung predominant
Prognosis usu. good if allergen exposure eliminated
Clin. DDx other diffuse lung diseases, esp. idiopathic pulmonary fibrosis
Treatment eliminate allergen exposure

It is also known as extrinsic allergic alveolitis, abbreviated EAA.

General

Microscopic

Features:

  • Lesions have centrilobular prominence - important feature. [3]
    • Allergens enter lung through airway which has a centrilobular location.
  • Granulomata (not typically seen in UIP) - important feature.[3]
  • Chronic interstitial inflammation consisting primarily of lymphocytes.
  • Interstitial fibrosis.
  • Air space involvement (alveolitis).

DDx:

Images

See also

References

  1. Kaltreider, HB. (Nov 1993). "Hypersensitivity pneumonitis.". West J Med 159 (5): 570-8. PMID 8279154. http://www.ncbi.nlm.nih.gov/pmc/articles/pmid/8279154/?tool=pubmed.
  2. URL: http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/pufrm.html. Accessed on: 4 December 2011.
  3. 3.0 3.1 Ohtani, Y.; Saiki, S.; Kitaichi, M.; Usui, Y.; Inase, N.; Costabel, U.; Yoshizawa, Y. (Aug 2005). "Chronic bird fancier's lung: histopathological and clinical correlation. An application of the 2002 ATS/ERS consensus classification of the idiopathic interstitial pneumonias.". Thorax 60 (8): 665-71. doi:10.1136/thx.2004.027326. PMID 16061708.