Which condition might present with a "steeple sign" on a chest X-ray?

The "steeple sign" on a chest X-ray is primarily associated with croup, also known as laryngotracheobronchitis. This sign is characterized by the narrowing of the subglottic region of the airway, which can occur due to inflammation in conditions such as croup. The appearance resembles a steeple or a church spire, hence the name. In patients with croup, particularly viral croup, the inflammation leads to characteristic clinical features such as a "barking" cough, stridor, and hoarseness, all resulting from the swelling in the upper airway.

In contrast, conditions like bronchitis, pneumonia, and asthma do not typically present with this specific radiographic finding. Bronchitis may show bronchial wall thickening, pneumonia would typically show opacities or consolidations depending on the infectious agent, and asthma may demonstrate hyperinflation of the lungs rather than a steeple sign. Therefore, recognizing the "steeple sign" as a diagnostic indicator is essential in identifying croup and effectively differentiating it from other respiratory conditions.