IgG4-related disease: diagnostic methods and therapeutic strategies in Japan.

This review describes methods utilized in Japan to diagnose and treat patients with IgG4-related disease. A diagnosis of IgG4-related disease is based on elevated serum IgG4 concentration and an increased number of IgG4(+) plasma cells. Differentiating IgG4-related disease from other disorders, especially malignancy, is quite important. Consensus treatment in Japan consists of an initial dose of prednisolone at 0.5-0.6 mg/kg/day, followed by careful and gradual dose reduction. Most patients require maintenance treatment at 5 to 10 mg/day. Patients refractory to glucocorticoids are either truly refractory or have been misdiagnosed, therefore requiring reassessment.