A Case of Adult-Onset Still's Disease Treated with Monitoring of Serum Tacrolimus Levels.

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology. The mainstays of treatment are glucocorticoids (GCs) and non-steroidal anti-inflammatory drugs, although most cases are refractory to these conventional therapies. Immunosuppressants,such as methotrexate (MTX), cyclosporine A, tumor necrosis factor-α blockers, an interleukin (IL)-1 blocker, and an IL-6, receptor blocker, have been suggested in previous reports for the treatment of steroid-resistant AOSD. We report herein the case of an AOSD patient who was successfully treated with tacrolimus, another immunosuppressant, in combination with GC and MTX. Blood concentrations of tacrolimus were monitored because of the narrow therapeutic window.