Right middle lobe consolidation refers to consolidation in part (incomplete) or all (complete) of the right middle lobe.
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 and includes:
- adult respiratory distress syndrome (ARDS)
- interstitial pneumonias
Consolidation is usually obvious on CT with the anatomical location easy to define through visualisation of the pleural fissures, however features can be subtle on chest radiography.
Features of right middle lobe consolidation on CXR include:
- opacification of the right lower zone, that may abut and outline the inferior margin of the horizontal fissure
- indistinct appearance or obscuration of the right heart border (silhouette sign) (c.f. right lower lobe consolidation)
- normal (clear and distinct) right superior mediastinal contour (c.f. right upper lobe consolidation)
- normal (clear and distinct) right hemidiaphragm contour (c.f. right lower lobe consolidation)
- occasionally there may be obscuration of the medial aspect of the right hemidiaphragm
- air bronchograms
- on lateral CXR: triangular opacification between the horizontal (superiorly) and right oblique fissures (posteriorly)
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.
- 1. Holder LE. Right upper and middle lobe consolidation. Chest. 1973;63 (4): 613-4. Chest (citation) - Pubmed citation
- 2. Collins J, Stern EJ. Chest radiology, the essentials. Lippincott Williams & Wilkins. (2007) ISBN:0781763142. Read it at Google Books - Find it at Amazon
- 3. W. Richard Webb, Charles B. Higgins. Thoracic Imaging. (2010) ISBN: 9781605479767
Related Radiopaedia articles
- airspace opacification
- differential diagnoses of airspace opacification
- lobar consolidation
- lobar lung collapse