15-Year-Old With Fever

A 15-year-old girl presents to urgent care with complaints of fever, arthralgia, abdominal pain, and a widespread rash that developed over the last 2 days. The patient says that the pain in her knees is severe and debilitating. On examination, the patient has a temperature of 100.3°F (37.9°C) as well as maroon and violaceous, purpuric papules and plaques on the legs, buttocks, and face. Laboratory examination shows elevated erythrocyte sedimentation rate and C-reactive protein, proteinuria, and hematuria.

View the image below and consider what your diagnosis and next steps would be. Resolution of the case is described on the following page.