Difference between revisions of "Pneumonia"

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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.
 
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 + [[PMN]]s.<ref name=Ref_AoGP95>{{Ref AoGP|95}}</ref>
 
DDx:
*[[Aspiration pneumonia]] - aspirated material, usually lack microorganisms.
 
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==

Revision as of 02:52, 13 February 2016

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.

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

Chronic infectious pneumonia

General

Common microorganisms:[1]

Note:

  • All of the later ones are granulomatous.

Microscopic

Features:

Aspiration pneumonia

General

  • Not associated with microorganisms - though empiric antibiotics are relatively common to cover infectious pneumonias that cannot be excluded easily on clinical grounds.[2]
  • Usually seen in the context of a toxin and/or pathology that affects the swallowing and cough reflexes.[3]

Common associations:[3]

Other risk factors:[2]

  • Traumatic brain injury.
  • Seizure disorder.
  • Bowel obstruction.
  • Drugs.
  • Obesity.
  • Labour.

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:

  • Neutrophils.
  • Foreign material, e.g. plant matter.
  • +/-Foreign body giant cells.
  • +/-Microorganisms.

DDx:

Images

  • Aspiration pneumonia - 1 - (WC)

  • Aspiration pneumonia - 2 - (WC)

  • Aspiration pneumonia - 3 - (WC)

Cytomegalovirus pneumonia

Main article: Cytomegalovirus

General

  • Immunodeficiency.
  • Critical illness.[4]

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. ↑ 2.0 2.1 Raghavendran, K.; Nemzek, J.; Napolitano, LM.; Knight, PR. (Apr 2011). "Aspiration-induced lung injury.". Crit Care Med 39 (4): 818-26. doi:10.1097/CCM.0b013e31820a856b. PMID 21263315.
  3. ↑ 3.0 3.1 Ohrui, T. (Sep 2005). "Preventive strategies for aspiration pneumonia in elderly disabled persons.". Tohoku J Exp Med 207 (1): 3-12. PMID 16082150.
  4. ↑ 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.
  5. ↑ URL: http://www.pathologyoutlines.com/topic/lungnontumorCMV.html. Accessed on: 23 January 2012.
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