A previously healthy 6-year-old boy taking no regular medications presented to the emergency department with persistent fever and cough for 15 days. Six days prior to presentation, multiple vesiculobullous lesions appeared on his palms and soles. Three days later, he developed erythema; vesicles and erosions on his face, trunk, and limbs; erosions on his lips and oral mucosa; eyelid swelling; and blisters on his anal mucosa.
On presentation, his temperature was 38.7 °C (101.7 °F); heart rate, 125/min; blood pressure, 98/50 mm Hg; and oxygen saturation, 98% on room air. Physical examination revealed bilateral exudative conjunctivitis and white exudates on his tongue, posterior pharynx, and buccal mucosa. Erosions with overlying dried blood were noted around his eyes, lips, and anal mucosa. He had targetoid erythematous papules on his face and vesiculobullous lesions on his torso and extremities (Figure). Auscultation of his lungs revealed bilateral crackles. Laboratory testing showed a white blood cell count of 15 000/μL (82% neutrophils); erythrocyte sedimentation rate, 39 mm/h; and C-reactive protein level, 57.1 mg/L. A computed tomography scan of the chest revealed bilateral lower lobe infiltrates. Azithromycin (10 mg/kg daily, intravenously) was started.