A chest radiograph shows opacification of the right lower zone with the right heart border still visible. An air bronchogram is seen within the opacity. Which lobe is most likely consolidated?

• A Right upper lobe
• B Right lower lobe ✓
• C Right middle lobe
• D Left lower lobe

Explanation

Right lower lobe consolidation obliterates the right hemidiaphragm but preserves the right heart border, because the right heart border is formed by the right middle lobe, which is unaffected. The silhouette sign requires the two opacities to share a common border; since the right lower lobe is posterior, it does not abut the right heart border. Air bronchograms indicate patent airways within consolidated lung.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.