A 69-year-old man with a history of recurrent pancreatitis treated with corticosteroids now has increasing fatigue for 2 years. He does not drink alcohol and has no evidence of gallbladder disease. On examination, there are no abnormalities. Laboratory studies show his serum creatinine is 5 mg/dL and urea nitrogen is 48 mg/ dL. His serum IgG4 is elevated. Ultrasound imaging shows bilateral hydronephrosis. What is abdominal CT imaging most likely to show in this man?