Lobar consolidation is the term used to describe consolidation in one of the lobes of the lung. It infers a alveolar spead of disease and is most commonly due to pneumonia.
Consolidation refers to the alveolar airspaces being filled with fluid (exudate/transudate/blood), cells (inflammatory), tissue, or other material.
The list of causes of consolidation is broad but for complete consolidation of a lobe the most common cause is pneumonia. Infection spreads through the lobar through the pores of Kohn between alveoli but is limited from spreading between lobes by the visceral pleura.
Other causes include:
- pulmonary malignancy
- bronchial obstruction with no (or minimal collapse)
- endobronchial neoplasm
- bronchial stricture
- foreign body
- extrinsic compression from lymph nodes
- pulmonary hemorrhage
General features of consolidation on CXR include:
Specific lobar consolidation can be determined by the location of airspace opacification, pattern and the effect on adjacent structures (silhouette sign):
- right upper lobe consolidation
- right middle lobe consolidation
- right lower lobe consolidation
- left upper lobe consolidation
- left lower lobe consolidation
It must be remembered that the homogeneity of the consolidation will be influenced by any underlying lung disease.
Occasionally with complete lobar consolidation, there may be an increased volume of the affected lobe, rather than the more frequent collapse. When the fissures are outwardly convex, the appearance is referred to as the bulging fissure sign.
A mnemonic to remember the general features of consolidation is A2BC3.
- lobar collapse can be mistaken for lobar consolidation but collapse will show signs of volume loss and usually absence of air bronchograms
Related Radiopaedia articles
- airspace opacification
- differential diagnoses of airspace opacification
- lobar consolidation
- lobar lung collapse