Retroperitoneal fibrosis after surgery for aortic aneurysm in a patient with periarteritis nodosa: successful treatment with corticosteroids. A 54-year-old man with hepatitis B virus-related periarteritis nodosa developed retroperitoneal fibrosis with bilateral hydronephrosis 2.5 months after placement of an aortobifemoral prosthesis for abdominal aortic aneurysm. Retroperitoneal fibrosis disappeared after treatment with corticosteroids. This observation is interesting in the light of the hypothesis that retroperitoneal fibrosis is caused by vasculitis. 