A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 3-year-old boy presents to the emergency department with a ‘cough-like-a-seal bark’ and a high-pitched inspiratory noise that is audible without a stethoscope. His mother reports that his cough has worsened over the last few hours. The patient's blood pressure is 118/78 mm Hg, pulse is 90/min, respiratory rate is 35/min, and temperature is 38.3°C (101.1°F). On physical examination, the boy is sitting and leaning forward in apparent respiratory distress with suprasternal and intercostal retractions. Auscultation reveals inspiratory stridor without wheezing. He has a frequent barking cough and a hoarse voice when he speaks. What is a chest X-ray likely to show?
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A
Increased interstitial markingsIncorrect. Increased interstitial markings on chest radiograph suggest viral pneumonitis or interstitial lung disease, not the upper airway narrowing of croup.
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B
Lobar consolidation in the lingualIncorrect. Lobar consolidation in the lingula represents a focal pneumonia; croup does not produce lobar consolidation.
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C
Thumbprint sign on the lateral imageIncorrect. The thumbprint sign on lateral neck radiograph is the classic finding of epiglottitis, which would present with high fever, drooling, and dysphagia, not a barking cough.
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D
Steeple signCorrect. croup (laryngotracheobronchitis) causes subglottic narrowing that produces the steeple sign on AP neck radiography.
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E
Subglottic membrane on AP neck radiographIncorrect. A subglottic membrane is associated with acquired subglottic stenosis (e.g., post-intubation) rather than the symmetric viral-edema narrowing of croup; the radiographic hallmark of croup is the steeple sign from diffuse subglottic narrowing, not a discrete membranous structure.
↑ Tap an answer to reveal the reasoning
Answer: D. A 3-year-old with a barking (seal-like) cough, inspiratory stridor, hoarseness, and low-grade fever has croup (laryngotracheobronchitis), most commonly caused by parainfluenza virus. The narrowing is at the subglottic region (cricoid ring), the narrowest part of the pediatric airway. On a frontal neck radiograph, this subglottic narrowing produces the classic steeple sign, a tapered, pointed appearance of the tracheal air column.
The thumbprint sign on lateral neck radiograph describes epiglottitis (Haemophilus influenzae type b), which presents with rapid onset of high fever, drooling, dysphagia, and a sick-appearing toxic child in the tripod position. Although this child is sitting and leaning forward and has retractions, the barking cough and stridor without drooling and a normal-appearing epiglottis fit croup better than epiglottitis.
Lobar consolidation in the lingula describes pneumonia, which would produce different respiratory findings without barking cough. Increased interstitial markings suggest viral pneumonitis or atypical pneumonia, not croup. Pearl: croup gives steeple sign on AP neck film; epiglottitis gives thumbprint sign on lateral neck film.
**Why each option:**
**A.** Increased interstitial markings on chest radiograph suggest viral pneumonitis or interstitial lung disease, not the upper airway narrowing of croup.
**B.** Lobar consolidation in the lingula represents a focal pneumonia; croup does not produce lobar consolidation.
**C.** The thumbprint sign on lateral neck radiograph is the classic finding of epiglottitis, which would present with high fever, drooling, and dysphagia, not a barking cough.
**D.** Correct: croup (laryngotracheobronchitis) causes subglottic narrowing that produces the steeple sign on AP neck radiography.