Steroid-resistant adult-onset Still's disease which showed a quick response to methotrexate.

A case of steroid-resistant adult-onset Still's disease is herein reported. The patient consulted us because of night fever, arthralgia and evanescent rashes. She was diagnosed with adult-onset Still's disease, with a C-reactive protein (CRP) value of 29.5 mg/dL and serum ferritin level of 4500 ng/mL. The fever, rashes and arthralgia disappeared after medication of medium-dose oral prednisolone, however, the CRP value persisted at high levels, and the serum ferritin level nevertheless increased by 5200 ng/mL. Following the pulse therapy with corticosteroid, the CRP value decreased once but thereafter returned to a high level again. The serum ferritin level did not respond during that therapy. Finally, 10 days after starting the administration of methotrexate, the CRP value dramatically decreased from 7 mg/dL to 0.16 mg/dL, and thereafter the serum ferritin level started to decline, which thus enabled us to eventually taper the dose of oral prednisolone.