What is that rash?

摘要

CASE HISTORY A healthy 15-month-old girl presented to the emergency department with a 24-hour history of fever and rash. The initial blanching rash developed into non-blanching areas with associated leg swelling. She had received no recent medications, had no known drug allergies and no unwell contacts. On examination, she was feverish at 38.6°C, capillary refill time was <2 s with warm peripheries, heart rate 169 bpm and blood pressure 94/59 mm Hg. A palpable purpuric rash was evident on all four limbs and face (figure 1) although the trunk was spared. Her legs were tense and oedematous to the knee. Initial investigations: