A HEALTHY 21-month-old boy presented with a 4-day history of cough and a 2-day history of fever. His medical history was significant for being a seronegative 32-week term gestational product of a human immunodeficiency virus–positive mother, and for 1 hospitalization for gastroenteritis. During the course of his illness he had decreased oral intake and was observed to grab his throat and complain of pain, while playing with his toys and sucking on a pacifier. Physical examination findings showed his temperature was 35°C; heart rate, 100 beats per minute; respiratory rate, 28/min; and oxygen saturation rate, 100% while breathing room air. Examination of the lungs showed no stridor or wheezing, but he had hoarseness on vocalization. His neck was supple, with small, shotty, palpable lymphadenopathy, and his pharynx was mildly erythematous. Laboratory studies disclosed the following values: white blood cells, 4.3×109/L with a normal differential cell count. A radiograph of the lateral aspect of the neck (Figure 1) and laryngoscopic examination were performed (Figure 2).