Pneumonia of the Right Middle Lobe With Silhouette Sign

Pneumonia of the Right Middle Lobe With Silhouette Sign

This chest x-ray shows an infiltrate that appears to blend with the right heart border (silhouette sign). The silhouette sign indicates contiguous positioning of the 2 structures that have similar radiodensity; the part of the lung contiguous with the right heart border is the right middle lobe, so that is the part with the infiltrate and pneumonia.

SCIENCE PHOTO LIBRARY