Although it was not discussed in the Recommendations, in his talk Dr. Cron said that anakinra is "revolutionizing" the treatment of macrophage activation syndrome (MAS) in systemic JIA (Rheumatology 2011;50:417-9) Dr. Cron reported that he has used anakinra as initial therapy to treat two children with MAS, and he found dramatic reductions in ferritin levels and liver enzymes within 2 days of initiation.
Systemic JIA is a relatively rare disease, with a prevalence of about 1 in 10,000. It has multiple systemic manifestations, including a high fever (which follows a unique pattern: typically once-daily, late-afternoon spikes in 30% of patients at presentation), rash, hepatosplenomegaly, lymphadenopathy, pericarditis, pleural effusion, pulmonary vasculitis, and even CNS stroke or seizure. Stroke or seizure might be related to MAS, a widespread coagulopathy that occurs in about 50% of patients and can be fatal.
Another common finding is asymmetry of the jaw. According to Dr. Cron, up to 80% of children with all forms of arthritis, including systemic JIA, can have arthritis of the temporomandibular joint (TMJ). This is often a subtle finding that can be overlooked until significant erosion has occurred. However, early TMJ arthritis can be detected with magnetic resonance screening.
Dr. Cron is a consultant for Genentech.