Successful re-administration of tocilizumab in a patient with adult-onset Still's disease after improvement of macrophage activation syndrome.

Tocilizumab (TCZ) is effective for inducing remission in adult-onset Still's disease (AOSD), but its use may occasionally trigger macrophage activation syndrome (MAS). The rationale for re-introducing TCZ in patients with a history of MAS is not well established. Here, we report a case of successful re-administration of TCZ for an AOSD relapse in a patient with a prior history of MAS during TCZ therapy. A 67-year-old woman, initially treated with TCZ for polyarthritis, developed MAS associated with AOSD. MAS was resolved with glucocorticoid pulse therapy, high-dose glucocorticoids, and cyclosporine A. However, AOSD relapsed during glucocorticoid tapering. Methotrexate, cyclosporine A, and repeated glucocorticoid pulses failed to control the disease. Following another glucocorticoid pulse, TCZ (8 mg/kg weekly) was re-introduced intravenously. This approach allowed successful glucocorticoid tapering and long-term remission. This case highlights the complexities of managing AOSD: while the initial TCZ therapy may have contributed to the onset of MAS, the subsequent re-introduction of TCZ enabled effective disease control and sustained remission.