Viral Infections USMLE Step 1 Practice Question
A 4-year-old boy presents with fever (38.9°C), barky cough, and inspiratory stridor. Vital signs show HR 115/min, RR 28/min, BP 105/68 mmHg, and SpO2 98% on room air. Lateral neck radiograph demonstrates subglottic narrowing with the characteristic "croup sign." Nasopharyngeal swab reverse transcription PCR is positive for parainfluenza virus type 1. There is no drooling or difficulty swallowing. Which of the following best describes the pathophysiology of his airway obstruction?
Answer choices
- AEpiglottic swelling and supraglottic edema
- BLaryngeal paralysis from viral myositis
- CPseudomembrane formation in the pharynx
- DSubepithelial edema and inflammation of the subglottic tracheaCorrect answer
- ETracheal stricture from chronic inflammation
- FEpiglottitis causing supraglottic swelling with thumbprint sign
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