Difference between revisions of "Pneumonia"

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[[Image:Acute pneumonia - i -- low mag.jpg|thumb|Acute pneumonia. [[H&E stain]]. (WC)]]
'''Pneumonia''' is inflammation of the lung, which includes infectious and non-infectious etiologies.   
'''Pneumonia''' is inflammation of the lung, which includes infectious and non-infectious etiologies.   


It is a subset of the [[medical lung diseases]].  This article primarily deals with the infectious pneumonias.  Idiopathic interstitial pneumonias are discussed very briefly; they are dealt with in detail in the ''[[diffuse lung diseases]]'' article.
It is a subset of the [[medical lung diseases]].  This article primarily deals with the infectious pneumonias.   
 
Idiopathic interstitial pneumonias are listed at the bottom; they are dealt with in detail in the ''[[diffuse lung diseases]]'' article.


=Infectious pnemonia=
=Infectious pnemonia=
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==Acute infectious pneumonia==
==Acute infectious pneumonia==
===General===
{{Main|Acute infectious pneumonia}}
*This is seen by pathologists, in [[autopsy]], from time-to-time.
The most common form of pneumonia. It is usually diagnosed clinically.
 
Most common cause:
*''Streptococcus pneumoniae''.<ref name=Ref_PBoD8_711>{{Ref PBoD8|711}}</ref>
 
The top three community acquired (acute) pneumonia:<ref name=pmid12239229>{{Cite journal  | last1 = Nicolau | first1 = D. | title = Clinical and economic implications of antimicrobial resistance for the management of community-acquired respiratory tract infections. | journal = J Antimicrob Chemother | volume = 50 Suppl S1 | issue =  | pages = 61-70 | month = Sep | year = 2002 | doi =  | PMID = 12239229 }}</ref>
*''Streptococcuc pneumonia''.
*''Haemophilus influenzae''.
*''Moraxella catarrhalis''.
 
Other community acquired pneumonia:<ref name=Ref_PBoD8_711>{{Ref PBoD8|711}}</ref>
*S. aureus.
*Legionaella pneumophila.
*Klebsiella pneumoniae.
*Pseudomonas.
 
Hospital-acquired pneumonia:<ref name=Ref_PBoD8_711>{{Ref PBoD8|711}}</ref>
*Gram-negative rods.
*''Staphylococcus aureus''.
 
===Radiologic correlate===
*Air space disease.
 
===Gross pathology===
*Consolidation (the lung parenchyma is firm) - best appreciated by running a finger over the cut surface of the lung with a small-to-moderate amount of pressure.
 
Bronchopneumonia:
*Classically yellow-white centered on the bronchi.<ref>{{Ref AoGP|93}}</ref>
 
Lobar pneumnia is classically described in four stages:<ref>{{Ref AoGP|92}}</ref><ref>URL: [http://www.histopathology-india.net/Lobar_Pneumonia.htm http://www.histopathology-india.net/Lobar_Pneumonia.htm]. Accessed on: 27 February 2012.</ref>
#Congestion - day 1-2.
#Red hepatization - day 2-4.
#Gray hepatization - day 4-6.
#Resolution - day 6+.
 
Note:
*The stages of lobar pneumonia is considered more-or-less historical. In the age of antibiotics, lobar pneumonia is uncommon.
 
===Microscopic===
Features:
*Alveoli packed with [[PMN]]s.
*+/-Clusters of bacteria - small dots or rods.
*+/-Abscess formation.
**Lung abscess = destruction of parenchyma + PMNs.<ref name=Ref_AoGP95>{{Ref AoGP|95}}</ref>
 
Image:
*[http://commons.wikimedia.org/wiki/File:Pneumonia_alveolus.jpg Normal alveoli & pneumonia (WC)].
 
===Stains===
*Gram stain -- to type the bacteria.


==Chronic infectious pneumonia==
==Chronic infectious pneumonia==
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*+/-[[Granuloma]]s.
*+/-[[Granuloma]]s.
==Aspiration pneumonia==
==Aspiration pneumonia==
===General===
{{Main|Aspiration pneumonia}}
*Usually seen in the context of a toxin and/or pathology that affects the swallowing and cough reflexes.<ref name=pmid16082150>{{Cite journal  | last1 = Ohrui | first1 = T. | title = Preventive strategies for aspiration pneumonia in elderly disabled persons. | journal = Tohoku J Exp Med | volume = 207 | issue = 1 | pages = 3-12 | month = Sep | year = 2005 | doi =  | PMID = 16082150 }}</ref>
**[[Stroke]].
**[[Multiple sclerosis]].
**[[Alcohol]].
 
*The microorganisms involved are usually different than in other causes of acute pneumonia.
 
Note:
*A special type of aspiration pneumonia is ''lipoid pneumonia''. It is dealt with in the ''[[lipoid pneumonia]]'' article.
 
===Gross===
*More common in the right lung.
**Right main stem bronchus is more vertical.
 
===Microscopic===
Features:
*+/-Foreign body giant cells.
*Microorganisms.
 
Images:
*[http://commons.wikimedia.org/wiki/File:Aspiration_pneumonia_%281%29.jpg Aspiration pneumonia - 1 - (WC)].
*[http://commons.wikimedia.org/wiki/File:Aspiration_pneumonia_%282%29.jpg Aspiration pneumonia - 2 - (WC)].
*[http://commons.wikimedia.org/wiki/File:Aspiration_pneumonia_%283%29.jpg Aspiration pneumonia - 3 - (WC)].


==Cytomegalovirus pneumonia==
==Cytomegalovirus pneumonia==

Latest revision as of 15:26, 5 March 2017

Acute pneumonia. H&E stain. (WC)

Pneumonia is inflammation of the lung, which includes infectious and non-infectious etiologies.

It is a subset of the medical lung diseases. This article primarily deals with the infectious pneumonias.

Idiopathic interstitial pneumonias are listed at the bottom; they are dealt with in detail in the diffuse lung diseases article.

Infectious pnemonia

Anatomical classification of pneumonia

  • Generally, not used by clinicians.
  • Use of the terms without qualification is discouraged... as they do not make explicit the etiology.

Bronchopneumonia

  • Multiple foci of (acute) inflammation involving the bronchi.
  • This is the most common form of (infectious) pneumonia.

Lobar pneumonia

  • Pneumonia that involves a whole lobe.
  • Rarely seen in areas where antibiotic treatments are widely available.

Acute infectious pneumonia

Main article: Acute infectious pneumonia

The most common form of pneumonia. It is usually diagnosed clinically.

Chronic infectious pneumonia

General

Common microorganisms:[1]

Note:

  • All of the later ones are granulomatous.

Microscopic

Features:

Aspiration pneumonia

Main article: Aspiration pneumonia

Cytomegalovirus pneumonia

Main article: Cytomegalovirus

General

  • Immunodeficiency.
  • Critical illness.[2]

Microscopic

Features:

  • CMV nuclear changes:
    • Large red nucleus with a pale halo.
  • Eosinophilic granular cytoplasmic inclusions.

Images:

IHC

  • CMV +ve -- cytoplasmic inclusions, large nucleus.

Diffuse lung diseases

Main article: Diffuse lung disease
  • AKA idiopathic interstitial pneumonia.

Histologic pattern:

See also

References

  1. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 711. ISBN 978-1416031215.
  2. ↑ Limaye, AP.; Boeckh, M. (Nov 2010). "CMV in critically ill patients: pathogen or bystander?". Rev Med Virol 20 (6): 372-9. doi:10.1002/rmv.664. PMID 20931610.
  3. ↑ URL: http://www.pathologyoutlines.com/topic/lungnontumorCMV.html. Accessed on: 23 January 2012.
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