Lobar Pneumonia vs Bronchopneumonia

What is lobar pneumonia?

Lobar pneumonia is a lung infection that affects an entire lung lobe or a large and continuous part of it ^[1]. When it affects more than one lobe, it is called multilobar, and when it affects all lung lobes, it is called panlobar pneumonia.

Causes

Lobar pneumonia is most often caused by bacteria, such as Streptococcus pneumoniae or Haemophilus influenzae, but also by other bacteria, such as Klebsiella, Mycoplasma or Legionella, or viruses ^[1].

Histology

Lobar pneumonia has 4 stages ^[1]:

Congestion in the first 24-48 hours with engorgement of the lung blood vessels and fluid in the air sacs (alveoli).
Red hepatization or consolidation (2nd-4th day) with fluid, red cells, white cells called neutrophils, and fibrin in the air sacs. Under the microscope, the lung tissue has the appearance of liver tissue (in Latin, liver = hepar, so from here the term hepatization)
Grey hepatization (4th-6th day) with breakdown of red liver cells and persistence of neutrophils and fibrin in the air sacs
Resolution (8th-9th day) = complete recovery

Symptoms and Signs

Symptoms of lobar pneumonia usually develop suddenly and can include coughing up yellow, green or rusty mucus, shortness of breath, high fever, fatigue and chest pain during coughing.

During percussion (tapping the chest with a finger), a doctor can hear a dull sound and during listening the lungs (auscultation), crackling sounds and decreased breathing sounds over the affected lung lobe.

X-Ray

On an X-ray, lobar pneumonia appears as a continuous white patch in a lung lobe.

Picture 1. Lobar pneumonia in the middle lobe
of the right lung – an X-ray image from the right side,
showing a triangular white patch (source: Radiopedia, CC license)

NOTE: The pattern of lobar pneumonia on X-ray film does not already mean a bacterial cause.

Treatment

Treatment of lobar pneumonia depends on the cause — bacterial pneumonia is treated with antibiotics and viral pneumonia by antivirals.