Risk of significant cytopenias after treatment with tocilizumab in systemic juvenile arthritis patients with a history of macrophage activation syndrome

Tocilizumab (tcz) is the first fda- approved treatment for systemic juvenile idiopathic arthritis (sjia). we report 3 cases of cytopenias in children with sjia treated with tcz. two of the children who developed significant cytopenias shortly after initiation of tcz had a history of macrophage activation syndrome. we raise the possibility that patients with a tendency towards mas have an increased risk of developing cytopenias when treated with tocilizumab. © 2012 kessler et al.; licensee biomed central ltd.