Acute infectious pneumonia

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Acute infectious pneumonia is a common type of pneumonia. It is usually diagnosed clinically and uncommonly biopsied.

General

Clinical features:

Dyspnea.
Chest pain.
Fever.

It is seen by pathologists at autopsy from time-to-time, and in advanced lung cancer.

Etiology

Most common cause:

Streptococcus pneumoniae.^[1]

The top three community acquired (acute) pneumonia:^[2]

Streptococcuc pneumonia.
Haemophilus influenzae.
Moraxella catarrhalis.

Other community acquired pneumonia:^[1]

S. aureus.
Legionaella pneumophila.
Klebsiella pneumoniae.
Pseudomonas.

Hospital-acquired pneumonia:^[1]

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.^[3]

Lobar pneumnia is classically described in four stages:^[4]^[5]

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 PMNs.
+/-Clusters of bacteria - small dots or rods.
+/-Abscess formation.
- Lung abscess = destruction of parenchyma + PMNs.^[6]

DDx:

Aspiration pneumonia - aspirated material, usually lack microorganisms.

Images

Normal alveoli & pneumonia. (WC)

AP - low mag. (WC)
AP - intermed. mag. (WC)
AP - intermed. mag. (WC)
AP - high mag. (WC)
AP - very high mag. (WC)

Stains

Gram stain -- to type the bacteria.

References

↑ ^1.0 ^1.1 ^1.2 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.
↑ Nicolau, D. (Sep 2002). "Clinical and economic implications of antimicrobial resistance for the management of community-acquired respiratory tract infections.". J Antimicrob Chemother 50 Suppl S1: 61-70. PMID 12239229.
↑ Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 93. ISBN 978-0521868792.
↑ Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 92. ISBN 978-0521868792.
↑ URL: http://www.histopathology-india.net/Lobar_Pneumonia.htm. Accessed on: 27 February 2012.
↑ Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 95. ISBN 978-0521868792.

[Ref_PBoD8_711-1] 1.0 ^1.1 ^1.2 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.

[pmid12239229-2] Nicolau, D. (Sep 2002). "Clinical and economic implications of antimicrobial resistance for the management of community-acquired respiratory tract infections.". J Antimicrob Chemother 50 Suppl S1: 61-70. PMID 12239229.

[3] Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 93. ISBN 978-0521868792.

[4] Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 92. ISBN 978-0521868792.

[5] URL: http://www.histopathology-india.net/Lobar_Pneumonia.htm. Accessed on: 27 February 2012.

[Ref_AoGP95-6] Rose, Alan G. (2008). Atlas of Gross Pathology with Histologic Correlation (1st ed.). Cambridge University Press. pp. 95. ISBN 978-0521868792.

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Acute infectious pneumonia

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