This protocol addresses the next clinical step in patients with idiopathic retroperitoneal fibrosis (RPF) occurring as part of IgG4-related disease (IgG4-RD), presenting with ureteral obstruction, where the first-line corticosteroid-based regimen has not achieved adequate disease control.
Most idiopathic RPF is now considered part of the IgG4-RD spectrum. Serum IgG4 serves as a key monitoring marker during treatment. When ureteral obstruction is present, urinary drainage alongside systemic therapy is typically required, and a good renal outcome is generally expected with appropriate management.
The first-line approach combined urinary drainage (ureteral stenting or percutaneous nephrostomy) with a prednisolone induction and taper. This next-line protocol applies when that regimen has not achieved:
For glucocorticoid-refractory idiopathic RPF with IgG4-RD, salvage immunosuppressive therapy is the basis of the next step. There is no single consensus agent; certain targeted immunosuppressive options have shown promise specifically in IgG4-RD. The complete agent selection and structured sequencing are available in the full protocol.
Currently, most idiopathic RPF is considered to be a part of this disease spectrum.
In IgG4RD, the serum IgG4 level is helpful to control the dosage of glucocorticoid.
Generally, in idiopathic RPF causing ureteral obstruction, a good outcome for renal function is expected, although long-term steroid therapy along with urinary drainage is often required.
For glucocorticoid-refractory disease, there is no consensus about salvage treatment.
The effectiveness of other immunosuppressive drugs, such as mycophenolate mofetil, cyclophosphamide, azathioprine, methotrexate and tacrolimus, has been reported.
In addition, rituximab, an anti-CD20 antibody, is promising for treatment of IgG4RD according to several reports.
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