Review Question - QID 216761

A 2-year-old boy is brought to the emergency department by his parents with a 2-day history of fever, rash, and irritability. Yesterday, his mother noticed that he appeared more fatigued and had a fever. This morning, she found him crying and complaining of pain with a diffuse rash. The patient is otherwise healthy and does not take any medications. His temperature is 103°F (39.4°C), blood pressure is 60/45 mmHg, pulse is 152/min, respirations are 26/min, and oxygen saturation is 100% on room air. Physical exam reveals the rash seen in Figure A, which is noted to cover more than 30% of the patient’s body surface. There are no lesions inside the mouth. Which of the following is the most likely diagnosis?