Hydronephrosis associated with retroperitoneal fibrosis and sclerosing pancreatitis.

Sclerosing pancreatitis is associated with raised concentrations of IgG4. We treated 22 patients with sclerosing pancreatitis, and identified and followed-up three with concomitant hydronephrosis caused by ureteral mass, later diagnosed as retroperitoneal fibrosis. We histologically examined the ureteral and pancreatic lesions of these patients and noted abundant infiltration of IgG4-bearing plasma cells in both tissues. Treatment with corticosteroids lowered serum concentrations of IgG4. IgG4 might also have a pathological role in a systemic fibrosing process that includes pancreatic and retroperitoneal lesions.