OBJECTIVEMacrophage activation syndrome (MAS) is a rare but life-threatening complication in children with rheumatic diseases, particularly systemic-onset juvenile idiopathic arthritis (SOJIA). Because of the potential fatality of this condition, prompt recognition and immediate therapeutic intervention are important. This study reviewed the data of MAS in 13 cases with SOJIA.

METHODSRetrospective review was performed on the precipitating events, clinical manifestations, laboratory data, treatment, and outcome of macrophage activation syndrome in 13 children with SOJIA seen from 1996 to 2005.

RESULTSOver the past 10 years the unit has had 90 new patients with SOJIA. Thirteen of those patients (14.4%) developed MAS during the course of their primary SOJIA, of whom ten were male. All patients were noted to have active SOJIA prior to developing MAS; 3 patients had medications, which were considered as trigger factors; 8 had infections prior to MAS, in two of them the infections were possible triggers. All the patients had high grade fever; 12 cases (92.3%) had hepatomegaly; 10 patients (76.9%) had coagulopathy, and eight patients (61.5%) had central nervous system dysfunction. The counts of platelet, white blood cells and the mean erythrocyte sedimentation rate fell dramatically in all patients; hyperferritinemia was identified in 8 patients, in 5 of whom serum ferritin (SF) was >or= 10,000 microg/L; in 8 (72.7%) of 11 cases fibrinogen was or= 2.5 mmol/L in 9 (69.2%) of 13 cases.

CONCLUSIONMAS is a rare and potentially fatal complication of children with SOJIA. Primary disease activity, medications and infections preceding MAS were all important triggers. The strongest clinical discriminators were hepatomegaly, hemorrhages and central nervous system dysfunction. The strongest laboratory tests were decreased counts of platelet and white blood cells, decreased ESR and fibrinogen, dramatically increased SF and TG. It calls for the immediate treatments, particularly with cyclosporin A, which are often effective.