Croup (or laryngotracheobronchitis) is a respiratory condition that is usually triggered by an acute viral infection of the upper airway. The infection leads to swelling inside the throat, which interferes with normal breathing and produces the classical symptoms of a “barking” cough, stridor, and hoarseness. It may produce mild, moderate, or severe symptoms, which often worsen at night. It is often treated with a single dose of oral steroids; occasionally inhaled epinephrine is used in more severe cases. Hospitalization is rarely required.  “Steeple Sign” is the term used to describe the appearance of the conus elasticus in the subglottis in plain films.