[Clinical Evaluation of Diagnostic and Treatment Protocol of Idiopathic Retroperitoneal Fibrosis Incorporating Consideration of Possible IgG4-Related Disease].

About half of idiopathic retroperitoneal fibrosis might be classified as a IgG4-related disease, a newly characterized disease that is especially known to be sensitive to steroid therapy. We developed a new protocol for diagnosis and treatment of retroperitoneal fibrosis, which included aggressive diagnosis of IgG4- related disease. We retrospectively reviewed 22 cases with idiopathic retroperitoneal fibrosis that were diagnosed and treated according to our protocol. Of them, 10 patients (45.5%) had no evidence of IgG4- related disease (non-IgG4RD group), whereas 12 patients (54.5%) were diagnosed with IgG4-related disease (IgG4RD group). All patients received steroid therapy, and 13 patients (59.1%) underwent ureteral stenting or received prednisolone (PNS). There was no severe adverse event and planned steroid therapy was completed in all patients. In principle, maintenance steroid therapy was continued after induction therapy in the IgG4RD group, whereas steroid therapy was discontinued in the non-IgG4RD group. Regression of retroperitoneal plaque was achieved in all 22 patients. Four (57.1%) out of 7 patients and 3 (50.0%) out of 6 patients achieved freedom from ureteral stent or PNS in the non-IgG4RD group and IgG4RD group, respectively. All 3 patients with PNS became catheter-free after treatment, whereas only 4 (40.0%) of the 10 patients withureteral stent could become stent-free. Steroid therapy could be discontinued in 7 patients (70.0%) in the non-IgG4RD group. The results of this study suggest that similar efficacy of steroid therapy can be expected in the non-IgG4RD group and IgG4RD group.