Progressive Rash and Arthralgias in a Teenage Male

PT Video: A short course of steroids was ineffective. He returns to ED c/o worsening joint and abdominal pain. Can you Dx?

A 16 y/o male presents with 9 days palpable, purpuric, non-pruritic rash that began on legs and spread quickly upwards; also c/o polyarticular arthritis, abdominal pain. Mild improvement after short course of steroids, finished 2 days ago. Joint/abdominal pain now worse. PMH, noncontributory; no sick contacts. What else do you need to know?


What is your initial impression?