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Lobar Pneumonia (Right Middle Lobe)

Updated: Nov 29, 2021

Chest X-ray Findings


The presence of fluid density material within the right middle lobe results in a wedge-shaped opacity in the right lower zone adjacent to the heart. Note the superior border of the opacity is sharply demarcated at the level of the horizontal fissure.

Air Bronchograms

Another finding, that is a little more difficult to appreciate, is the presence of air bronchograms. Air filled bronchi that are surrounded by alveolar infiltrates can appear as dark, radiolucent branching columns within the area of opacification.

Silhouette Sign

Consolidation of the right middle lobe results in effacement of the right heart border; obscuring the interface between the lung and heart. This is referred to as the silhouette sign.

Also note that the superior border of the right hemidiaphragm is clearly defined. This helps to differentiate a right middle lobe pneumonia from a right lower lobe pneumonia, in which case the right hemidiaphragm would be obscured.

Normal/Increased Lung Volume

Unless there is coinciding atelectasisi, there usually is no loss of lung volume.


Radiographic evidence of often pneumonia worsens during the first few days of treatment and can take several weeks to completely resolve.

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