Novel use of rituximab in macrophage activation syndrome secondary to systemic lupus erythematosus.

Macrophage activation syndrome (MAS) is a rare disease characterised by aberrant immune hyperactivation of T lymphocytes and macrophages driven by cytokine dysfunction. The HLH-2004 protocol is commonly used for the treatment of MAS, but significant toxicities are associated. We describe a case of MAS secondary to systemic lupus erythematosus in a young female that responded well to rituximab in lieu of etoposide. She continues to be in remission 1 year following the completion of rituximab infusion and is maintained on hydroxychloroquine. This case highlights the need for further research on the use of rituximab and other available biologics in the setting of MAS in order to help guide further alternative treatment decisions.