Thumb sign
Head & NeckRadiograph
A swollen, rounded epiglottis projects into the airway on a lateral neck radiograph, resembling the tip of a thumb.
What it means
Epiglottitis, a potentially life-threatening supraglottic infection.
Mechanism
Inflammatory swelling thickens and rounds the normally thin, curved epiglottis so it resembles a thumb.
Associated conditions
- Acute epiglottitis
- Haemophilus influenzae type b infection
- Supraglottitis
- Thermal or caustic epiglottic injury
Pearls
- Airway management takes priority; avoid distressing the child for imaging.
- Look also for thickened aryepiglottic folds on the lateral view.
References
- Radiopaedia: Thumb sign (epiglottitis)
For educational use only. This dictionary is a study aid and reference, not a diagnostic tool, and must not be used to guide clinical decisions or patient care. Imaging appearances vary; always correlate with the full clinical picture and confirm with a qualified radiologist.