What radiographic sign is associated with epiglottitis on lateral neck radiograph?

• A. Thumb sign
• B. Steeple sign
• C. Double bubble sign
• D. Kerley B lines

Answer: (A)

The main idea is how the epiglottis looks on a side view when it’s inflamed. In epiglottitis, the epiglottis becomes markedly enlarged and pushes forward into the airway, and on a lateral neck radiograph this appears as a smooth, rounded projection resembling a thumb—the classic “thumb sign.” This bright, forward-projecting shadow reflects edema and swelling of the epiglottis and surrounding pre-epiglottic space, which is why this sign is the best clue on the lateral view.

Other signs point to different conditions: the steeple sign is a frontal-view finding of subglottic narrowing seen with croup, not epiglottitis; the double bubble sign indicates duodenal atresia; Kerley B lines reflect interstitial edema in the lungs.