Significance of the 'thumbprint sign' in lateral neck X-rays?

• A. It indicates epiglottitis
• B. It indicates retropharyngeal abscess
• C. It indicates croup
• D. It indicates airway edema

Answer: (A)

The thumbprint sign reflects swelling of the epiglottis. On a lateral neck radiograph, an acutely inflamed epiglottis becomes thick and rounded, projecting into the airway and producing a smooth, thumb-shaped contour. This classic appearance points to epiglottitis (supraglottitis), a potentially life-threatening airway emergency requiring prompt airway assessment and treatment with antibiotics.

Other conditions have different radiographic patterns: a retropharyngeal abscess tends to widen the prevertebral space, croup often shows a steeple sign on an AP view rather than a lateral thumbprint, and general airway edema does not produce the distinctive enlarged epiglottis appearance.