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Macrophage activation syndrome (MAS) is a life-threatening complication in children with rheumatic diseases, particularly systemic-onset juvenile chronic arthritis (SOJCA). Because of the potential fatality of this condition, prompt recognition and immediate therapeutic intervention are important. This study assessed the clinical features of nine MAS events in five children with SOJCA. Nonremitting fever and decreased platelet and white blood cell counts led to a diagnosis of MAS. The urinary beta2-microglobulin (beta2MG) level was a sensitive indicator of MAS. Serum levels of beta2MG and soluble interleukin-2 receptor were also elevated. These biologic markers reflecting hyperactivated cellular immunity are useful indicators of MAS. Four children treated with cyclosporin A (CSP) achieved rapid and complete recovery, but one patient without CSP died due to rapidly progressive respiratory failure. All children treated with CSP responded quickly, and fever abated within 36 h of initiation of treatment. CSP should be added to first-line therapy of MAS., (Copyright 2005 S. Karger AG, Basel)

Administration of salicylates during prodromal viral illness has been associated with the development of Reye's syndrome (RS). We studied salicylate biotransformation in RS patients and compared it with those on chronic salicylate therapy for juvenile rheumatoid arthritis (JRA). Urine of RS patients contained significantly more salicylic acid and less gentisic acid than that of JRA patients while the conjugated metabolites were not different between the two groups. These results suggest decreased salicylate microsomal oxidation in RS. The role of altered salicylate metabolism in the pathogenesis of RS is unclear.