The incidence of macrophage activation syndrome in children with rheumatic disorders.

AIM: Macrophage activation syndrome (MAS) is a rare complication of childhood with rheumatic disease. This syndrome has been reported as a complication of many rheumatic diseases, most commonly in systemic onset of juvenile idiopathic arthritis (SoJIA). The aim of this study was evaluation the rate, symptoms and outcome of MAS in a pediatric rheumatology department in Tehran during 10 years.
METHODS: Retrospective review of cases of MAS from the charts of 120 patients with juvenile idiopathic arthritis and systemic lupus erythematosus (SLE). Collected data base of 5 children with MAS from 1998 to 2007, in Children Hospital Medical Center, In Tehran University were collected.
RESULTS: Totally 120 patients evaluated in this study including 108 JIA and 12 SLE. Five patients (four girls), and (one boy) were considered to have evidence of MAS. The incidence of MAS in our study was 4.2%. This rate for all JIA patients was 3.7% and for SoJIA, SLE and juvenile idiopaticarthritis (JIA) and polyarticular RF negative JIA was 8.2%, 16.7% and 2.8%, respectively. Mean age of MAS onset was 4.9 years, and duration of rheumatologic disease prior to MAS, 22 months. Four cases (80%) had abnormal liver function during the disease course, and coagulopathy. Bone marrow examination supported the diagnosis with definite haemophagocytosis in four cases (80%). The mortality rate was 40%.
CONCLUSION: Although MAS is a rare complication of rheumatologic disorders, because it is potentially fatal it must be thought in each childhood rheumatic disorders with suddenly changes in general condition and decrease peripheral cells.