On a lateral neck radiograph, which sign is classically associated with epiglottitis?

• A. Steeple sign
• B. Ground glass sign
• C. Thumbprint sign
• D. Double bubble sign

Answer: (C)

The key idea is that epiglottitis causes pronounced swelling of the epiglottis, which on a lateral neck radiograph appears as a thick, rounded, posterior shadow—the thumbprint of the swollen epiglottis. This thumbprint sign is the classic radiographic clue that points to supraglottitis in the airway. In contrast, other signs help with different conditions: the steeple sign, seen on an AP neck view, reflects subglottic narrowing typical of croup; the remaining options don’t describe airway inflammation in this region. Thus, recognizing a thick, rounded epiglottic shadow on the lateral view—the thumbprint sign—best identifies epiglottitis.