This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
Thumb sign in lateral X-ray of neck seen in: 
Select and explain. 
A. Epiglottitis, B. Internal hemorrhage, C. Saccular cyst, D. Ca epiglottis
A: Epiglottitis
Answer: A: Epiglottitis 
Explanation: In epiglottis: A plain lateral soft tissue radiograph of neck shows the following specific features Thickening of the epiglottis--the thumb sign Absence of a deep well-defined vallecula--the vallecula sign Steeple sign i.e. Narrowing of subglottic region is seen in chest X-ray of patients of laryngotracheobronchitis (i.e. croup).