Difference between revisions of "Hypersensitivity pneumonitis"

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#redirect [[Diffuse_lung_diseases#Hypersensitivity_pneumonitis]]
{{ Infobox diagnosis
| Name      = {{PAGENAME}}
| Image      = Hypersensitivity pneumonitis intermed mag.jpg
| Width      =
| Caption    = Hypersensitivity pneumonitis. Trichrome stain.
| Synonyms  = extrinsic allergic alveolitis
| Micro      = centrilobular prominence of lesions, [[granulomata]], chronic interstitial inflammation consisting primarily of lymphocytes, interstitial fibrosis, air space involvement (alveolitis)
| Subtypes  =
| LMDDx      = [[usual interstitial pneumonia]], [[asbestosis]]
| Stains    =
| IHC        =
| EM        =
| Molecular  =
| IF        =
| Gross      =
| Grossing  =
| Site      = [[lung]] - see ''[[diffuse lung diseases]]''
| Assdx      =
| Syndromes  =
| Clinicalhx = allergen exposure
| Signs      =
| Symptoms  =
| Prevalence = uncommon
| Bloodwork  =
| Rads      = upper lung predominant
| Endoscopy  =
| Prognosis  = usu. good if allergen exposure eliminated
| Other      =
| ClinDDx    = other [[diffuse lung diseases]], esp. [[idiopathic pulmonary fibrosis]]
| Tx        = eliminate allergen exposure
}}
'''Hypersensitivity pneumonitis''', abbreviated '''[[HP]]''', is a [[diffuse lung diseases]] caused by an allergen.
 
It is also known as '''extrinsic allergic alveolitis''', abbreviated '''EAA'''.
 
==General==
*Exposure to stuffs... e.g. moldy hay - ''Farmer's lung'', atypical mycobacteria - ''hot tub lung''.
*Upper lung predominant disease.
**Mnemonic ''FASSTEN'' - upper lung field: [[Farmer's lung]], [[Ankylosing spondylitis]], [[Sarcoidosis]], [[Silicosis]], [[Tuberculosis]] (miliary), [[Eosinophilic granuloma]], [[Neurofibromatosis]].
*An immune complex-mediated [[hypersensitivity]]<ref name=pmid8279154>{{Cite journal  | last1 = Kaltreider | first1 = HB. | title = Hypersensitivity pneumonitis. | journal = West J Med | volume = 159 | issue = 5 | pages = 570-8 | month = Nov | year = 1993 | doi =  | PMID = 8279154 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/pmid/8279154/?tool=pubmed }}</ref> (Gell-Coombs classification type III).
**If chronic, may develop into a cell-mediated hypersensitivity (Gell-Coombs classification type IV).<ref>URL: [http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/pufrm.html http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/pufrm.html]. Accessed on: 4 December 2011.</ref>
 
===Specific diseases/etiology===
Selected causes of hypersensitivity pneumonitis:<ref name=pmid21978856>{{cite journal |author=Zacharisen MC, Fink JN |title=Hypersensitivity pneumonitis and related conditions in the work environment |journal=Immunol Allergy Clin North Am |volume=31 |issue=4 |pages=769–86, vii |year=2011 |month=November |pmid=21978856 |doi=10.1016/j.iac.2011.07.004 |url=}}</ref>
{| class="wikitable sortable"
! Disease
! Cause
|-
| Silicosis
| silica exposure
|-
| |[[Asbestosis]]
| asbestos
|-
| Flavour-worker's lung (popcorn lung)
| diacetyl - used for butter flavour<ref name=pmid21618944>{{cite journal |author=Egilman DS, Schilling JH, Menendez L |title=A proposal for a safe exposure level for diacetyl |journal=Int J Occup Environ Health |volume=17 |issue=2 |pages=122–34 |year=2011 |pmid=21618944 |doi= |url=}}</ref>
|-
| [[Talcosis]]
|
|-
| Sick building syndrome
| volatile organic compounds, smoke, dampness
|-
| Berylliosis
| beryllium
|-
| Coal worker’s pneumoconiosis
| coal dust
|}
 
==Gross==
*Peripheral or peribronchiolar.<ref name=pmid16434894>{{Cite journal  | last1 = Churg | first1 = A. | last2 = Muller | first2 = NL. | last3 = Flint | first3 = J. | last4 = Wright | first4 = JL. | title = Chronic hypersensitivity pneumonitis. | journal = Am J Surg Pathol | volume = 30 | issue = 2 | pages = 201-8 | month = Feb | year = 2006 | doi =  | PMID = 16434894 }}</ref>
**Not large airways.
 
==Microscopic==
Features:
* Lesions have centrilobular prominence - '''important feature'''. <ref name=pmid16061708/>
** Allergens enter lung through airway which has a centrilobular location.
* [[Granulomata]] (not typically seen in UIP) - '''important feature'''.<ref name=pmid16061708>{{Cite journal  | last1 = Ohtani | first1 = Y. | last2 = Saiki | first2 = S. | last3 = Kitaichi | first3 = M. | last4 = Usui | first4 = Y. | last5 = Inase | first5 = N. | last6 = Costabel | first6 = U. | last7 = Yoshizawa | first7 = Y. | title = Chronic bird fancier's lung: histopathological and clinical correlation. An application of the 2002 ATS/ERS consensus classification of the idiopathic interstitial pneumonias. | journal = Thorax | volume = 60 | issue = 8 | pages = 665-71 | month = Aug | year = 2005 | doi = 10.1136/thx.2004.027326 | PMID = 16061708 }}</ref>
* Chronic interstitial inflammation consisting primarily of lymphocytes.
* Interstitial fibrosis.
* Air space involvement (alveolitis).
 
DDx:
*[[Usual interstitial pneumonia]].
*[[Nonspecific interstitial pneumonia]].
 
===Images===
<gallery>
Image:Hypersensitivity_pneumonitis_low_mag.jpg | Hypersensitivity pneumonitis - low mag. (WC/Nephron)
Image:Hypersensitivity_pneumonitis_intermed_mag.jpg | Hypersensitivity pneumonitis - intermed. mag. (WC/Nephron)
Image:Hypersensitivity_pneumonitis_high_mag.jpg | Hypersensitivity pneumonitis - high mag. (WC/Nephron)
</gallery>
 
==See also==
*[[Diffuse lung diseases]].
*[[Pneumoconioses]].
 
==References==
{{Reflist|2}}


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Diffuse lung diseases]]

Latest revision as of 19:06, 17 March 2015

Hypersensitivity pneumonitis
Diagnosis in short

Hypersensitivity pneumonitis. Trichrome stain.
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

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

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

General

Specific diseases/etiology

Selected causes of hypersensitivity pneumonitis:[3]

Disease Cause
Silicosis silica exposure
Asbestosis asbestos
Flavour-worker's lung (popcorn lung) diacetyl - used for butter flavour[4]
Talcosis
Sick building syndrome volatile organic compounds, smoke, dampness
Berylliosis beryllium
Coal worker’s pneumoconiosis coal dust

Gross

  • Peripheral or peribronchiolar.[5]
    • Not large airways.

Microscopic

Features:

  • Lesions have centrilobular prominence - important feature. [6]
    • Allergens enter lung through airway which has a centrilobular location.
  • Granulomata (not typically seen in UIP) - important feature.[6]
  • Chronic interstitial inflammation consisting primarily of lymphocytes.
  • Interstitial fibrosis.
  • Air space involvement (alveolitis).

DDx:

Images

  • Hypersensitivity pneumonitis - low mag. (WC/Nephron)

  • Hypersensitivity pneumonitis - intermed. mag. (WC/Nephron)

  • Hypersensitivity pneumonitis - high mag. (WC/Nephron)

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. ↑ Zacharisen MC, Fink JN (November 2011). "Hypersensitivity pneumonitis and related conditions in the work environment". Immunol Allergy Clin North Am 31 (4): 769–86, vii. doi:10.1016/j.iac.2011.07.004. PMID 21978856.
  4. ↑ Egilman DS, Schilling JH, Menendez L (2011). "A proposal for a safe exposure level for diacetyl". Int J Occup Environ Health 17 (2): 122–34. PMID 21618944.
  5. ↑ Churg, A.; Muller, NL.; Flint, J.; Wright, JL. (Feb 2006). "Chronic hypersensitivity pneumonitis.". Am J Surg Pathol 30 (2): 201-8. PMID 16434894.
  6. ↑ 6.0 6.1 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.
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