Macrophage activation syndrome after treatment with infliximab for fistulated Crohn's disease

Introduction Macrophage activation syndrome has never been reported as an adverse effect of infliximab. Case Treatment with infliximab was prescribed for a 37-year-old man with fistulated Crohn's disease unresponsive to azathioprine. Three months after the last injection, he developed macrophagic activation syndrome, with febrile pancytopenia, hyperferritinemia, hypertriglyceridemia and an activated cephalin time twice the control level. Discussion Elimination of the known causes of macrophage activation syndrome suggests it is related to the infliximab treatment, but its pathogenesis remains a mystery.