Prolonged Fever, Rash and Mucosal Bleeding

Macrophage activation syndrome (MAS) presents at onset in up to 22% of patients and in up to 50% in subclinical forms of systemic juvenile idiopathic arthritis (SJIA). About 10–15% of children with SJIA experinece at least one episode of MAS during their disease It is very difficult to distinguish SJIA/MAS from primary HLH, especially in a very young child An initially high ESR that then drops, despite increasing inflammation, is characteristic of MAS/HLH and thought to be secondary to decreasing fibrinogen level Currently there are no validated evidence-based guidelines on management of MAS in SJIA A short-term, high-dose intravenous methylprednisolone therapy is reported to be an effective first-line treatment