Pneumococcal pneumonia is the most common cause for lobar consolidation. The involved lobe goes through red hepatization and gray hepatization stages. In the lobar consolidation, an entire lobe is involved. The alveolar space is filled with inflammatory exudate made up of WBC, bacteria, plasma and debris. The airway is patent. In the stage of resolution, some secretions can be in the airway. The interstitium and architecture of the lung remain intact and complete recovery occurs. In early stages of consolidation the lung volume increases. In later stages there can be some amount of loss of lung volume due to secretions obstructing airways. As a general rule, there is no significant loss of lung volume in consolidation.

Radiologically this transcribes to the following:

• A density corresponding to a segment or lobe
• Airbronchogram
• No significant loss of lung volume