A 16-year-old African American boy presented to the emergency department with a 2-week history of an enlarging focus of erythema and induration over his right elbow. His symptoms reportedly began with the localized onset of pruritic papules that coalesced to form a large plaque. After 1 week, the region had become markedly indurated, with weeping of serous fluids, and the patient was seen by a local physician, who prescribed cephalexin. Despite the antibiotic therapy, the inflammation and induration continued to worsen.

At the time of presentation, the patient denied fever, chills, nausea, or fatigue. His medical history was significant for 2 prior episodes of presumed cellulitis involving the posterior aspect of the right upper extremity and the back of the neck that had occurred within the past 2 years. He reported that these episodes had resolved with oral antibiotic therapy. A clinical diagnosis of cellulitis of the right arm was made, and the patient was admitted to the hospital for treatment.