What radiographic sign is commonly seen on AP and lateral neck radiographs in croup?

• A. Thumbprint sign
• B. Steeple sign
• C. Air bronchograms
• D. Glottic swelling

Answer: (B)

In croup, inflammation and edema in the subglottic region narrow the upper trachea. This narrowing creates a characteristic shape on neck films known as the steeple sign. On an AP view, the tracheal air column tapers toward the distal subglottic area, producing a pointed, church-steeple look that is classic for subglottic narrowing from croup. On the lateral view, you can see the same subglottic narrowing contributing to a narrowed airway just below the vocal cords.

This sign is specific to the pattern of airway narrowing seen in croup. The thumbprint sign, by contrast, points to epiglottitis, where the epiglottis appears enlarged on a lateral view. Air bronchograms indicate air-filled bronchi within areas of consolidation, as seen in pneumonia or bronchiolitis, not the subglottic narrowing of croup. Glottic swelling is a general description and does not represent a distinct radiographic sign for croup on these views.