A child presents with supraglottic narrowing on a lateral neck x-ray. What condition is indicated by this finding?

Supraglottic narrowing observed on a lateral neck x-ray is indicative of epiglottitis. This condition is characterized by inflammation of the epiglottis, which can lead to swelling that obstructs the airway. During an x-ray evaluation, the classic finding in epiglottitis is the "thumbprint sign," where the swollen epiglottis appears enlarged, leading to the narrowing above the glottis.

This condition can present with symptoms such as high fever, drooling, and difficulty breathing, and it generally requires urgent medical intervention due to the risk of airway obstruction.

In contrast, while conditions like croup and laryngotracheobronchitis primarily involve subglottic narrowing, their typical x-ray findings are different and do not show the supraglottic swelling seen in epiglottitis. Pneumonia, on the other hand, primarily affects the lungs and does not relate directly to the airway structures observed in this context.