An 18-month-old with a seal-bark cough and dyspnea on a neck X-ray is most likely to show which sign?

• A. Steeple Sign
• B. Cullen Sign
• C. Thumbprint Sign
• D. Brudzinski's

Answer: (A)

Recognizing croup and its characteristic radiographic sign. In an 18‑month‑old with a seal-bark cough and dyspnea, viral laryngotracheobronchitis is most likely, causing subglottic edema. On an AP neck radiograph, this edema narrows the subglottic region, producing a pointed, tapered contour known as the steeple sign. This steeple appearance is the classic radiographic hallmark of croup and reflects the inflammation just below the vocal cords.

The other signs point to different conditions: a thumbprint sign suggests epiglottitis, Brudzinski's sign relates to meningitis, and Cullen sign indicates intra-abdominal bleeding or pancreatitis.