What is your treatment algorithm for management of retroperitoneal fibrosis that does not respond to high-dose glucocorticoids?

There are a number of caveats to this.

1. Is the retroperitoneal fibrosis biopsy-proven and/or IgG4 disease ruled out?
2. If a case is refractory, I first question whether the diagnosis is correct and will often biopsy in this situation with more than an FNA biopsy. The second question is how long have they been on high-dose corticosteroids. I typically reimage at 6-8 weeks and would not consider them a failure prior to that.
3. If biopsy-proven and steroids have been given for over 6-8 weeks, I will of...