[Systemic forms of idiopathic juvenile arthritis: clinical course].

UNLABELLED: FAVORABLE PROGNOSIS: The prognosis of systemic onset juvenile idiopathic arthritis varies. The most favorable outcome is observed when joint involvement is mild or delayed. No initial clinical or biological feature is indicative of severe prognosis except polyarticular involvement at onset. There is no HLA association. After 10 years follow-up, inflammatory features have disappeared in 50% of the cases, with some disability in 25%. POSSIBLE COMPLICATIONS: Some severe complications can occur during the course of systemic juvenile idiopathic arthritis: secondary amyloidosis (1 to 2%), spontaneous or drug-induced macrophage activation syndrome. Gold salts, sulfasalazine, or nonsteroidal antiinflammatory drugs may be implicated, associated or not with viral infection. Growth retardation is most often secondary to corticosteroid therapy. Long-term prognosis as published in various series mentions 8 to 14% mortality, secondary to iatrogenic accidents, infections or secondary amyloidosis.