A rare vasculitis that is fatal in adolescence turns out to be caused by a mutation in interferon that affects the JAK pathway. This has implications for other auto-inflammatory diseases including lupus.
A 5-year-old boy had pain and weakness in his legs and had trouble climbing stairs. He had a dramatic rise in CPK followed by erythematous papules on the hands, as shown, and a rash around the eyelids. Which diagnosis is most likely?