Silhouette Sign

The Silhouette Sign refers to a visual cue used in medical imaging, particularly in chest X-rays, to indicate the presence of disease. It occurs when the outline of an anatomical structure, like the heart or diaphragm, becomes less distinct due to nearby abnormal fluid or tissue density. When the normal silhouette is lost—meaning the borders are not clearly seen—it can suggest issues like pneumonia or a pleural effusion. Essentially, healthcare providers use this sign to help diagnose respiratory conditions by examining how structures appear and whether they maintain their expected outlines.