Disease course and treatment regimen. Initially, IVIG was administered on three consecutive days, 2 weeks apart. Arrowheads represent the time points of IVIG dosing (2 g/day). Rituximab was given at a dose of 375 mg/m2/week over three consecutive weeks, and then every 3 to 4 months (arrows). Plasma exchanges were initially performed four times per week, then gradually tapered to once a week and discontinued. They were restarted following a disease flare 7 months after diagnosis. The numbers represent the frequency of plasma exchanges per week. The large bold arrows indicate disease flares. CK = creatine kinase; CMAS = childhood myositis assessment scale; IVIG = intravenous immune globulins; MMF = mycophenolate mofetil; MMT = manual muscle testing; MTX = methotrexate.
