Case 2: A 13-year-old Boy with a Perplexing Rash

Presentation

A 13-year-old boy presents to the emergency department with a fever for 1 day and a worsening rash for 1 month. He initially took amoxicillin because the rash was thought to be due to scarlet fever. The amoxicillin was changed to azithromycin after 3 days due to concern for allergic reaction after the development of facial swelling. A week after completion of azithromycin therapy the patient was prescribed prednisone due to worsening of his rash, which became pruritic with drainage from some lesions. A review of systems is otherwise negative. The patient has no eczema, food, or drug allergies. He has no significant medical history other than a recent diagnosis of bipolar disorder for which he started taking carbamazepine 2 months before his presentation to the emergency department. He is up to date on his immunizations, without known sick contacts. Physical examination reveals an uncomfortable child in mild distress complaining of pruritus. His temperature is 102.2°F (39°C), heart rate is 134 beats/min, blood pressure is 117/69 mm Hg, respiratory rate is 20 breaths/min, and oxygen saturation is 99% on room air. He has a diffuse maculopapular erythematous rash over his torso and extremities (Fig). The rash is most concentrated on his face, neck, and upper trunk, with the flexural creases …