How would you approach management of retroperitoneal fibrosis causing ureteral compression that has already caused irreversible loss of kidney function?   

This is a difficult question. Is the mass only on the one side or present on the other but has not caused ureteral obstruction? Is the affected side able to be stented to save residual function? Was the patient treated medically previously and failed or is this a new diagnosis? I might try getting ...

There is a paucity of information about this patient with a diagnosis of RPF. Are we dealing with idiopathic RPF or IgG4-RPF? Approximately half the patients with RPF have IgG4-RPF. Was a biopsy done to confirm the diagnosis with histopathological examination and immunohistochemical staining for IgG...

I agree with my colleagues and will add some additional thoughts. While I agree that tissue diagnosis is helpful whenever it can be obtained (both to differentiate IgG4-related vs idiopathic RPF and to exclude other causes such as lymphoma, sarcoma, and Erdheim-Chester Disease), it is often the case...