Lobar pneumonia

This article is about Lobar pneumonia. For the disease in general, see Pneumonia. For classification, see Classification of pneumonia.
Lobar pneumonia
Figure A shows the location of the lungs and airways in the body. This figure also shows pneumonia affecting the lower lobe of the left lung. Figure B shows normal alveoli. Figure C shows infected alveoli.
Classification and external resources
Specialty pulmonology
ICD-10 J18.1
ICD-9-CM 481
MeSH D011018

Lobar pneumonia is a form of pneumonia that affects a large and continuous area of the lobe of a lung.[1]

It is one of the two anatomic classifications of pneumonia (the other being bronchopneumonia).


Micrograph of lobar pneumonia, H&E stain.

Lobar pneumonia usually has an acute progression. Classically, the disease has four stages:


Lobar pneumonia of the middle lobe. (Notice sharp edges)

The most common organisms which cause lobar pneumonia are Streptococcus pneumoniae, also called pneumococcus, Haemophilus influenzae and Moraxella catarrhalis. Mycobacterium tuberculosis, the tubercle bacillus, may also cause lobar pneumonia if pulmonary tuberculosis is not treated promptly.

Like other types of pneumonia, Lobar pneumonia can present as community acquired, in immune suppressed patients or as nosocomial infection. However, most causative organisms are of the community acquired type. Pathological specimens to be obtained for investigations include;

  1. Sputum- for culture, AAFBS and gram stain.
  2. Blood for full hemogram/complete blood count, ESR and other acute phase reactants.
  3. Procalcitonin test- More specific.

The identification of the infectious organism (or other cause) is an important part of modern treatment of pneumonia. The anatomical patterns of distribution can be associated with certain organisms,[2] and can help in selection of an antibiotic while waiting for the pathogen to be cultured.


  1. Cotran, Ramzi S.; Kumar, Vinay; Fausto, Nelson; Nelso Fausto; Robbins, Stanley L.; Abbas, Abul K. (2005). Robbins and Cotran pathologic basis of disease. St. Louis, Mo: Elsevier Saunders. p. 749. ISBN 0-7216-0187-1.
  2. "Lobar Pneumonia". Retrieved 2008-11-16.
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