Review Question - QID 212659

A 52-year-old man presents to the emergency department with a 12-hour history of flank pain. He says that the flank pain came on suddenly after dinner, but he went to bed thinking that it might go away in the morning. When he woke up in the morning, he had a fever and noticed blood in his urine so he came in for an evaluation. His past medical history is significant for diabetes and hypertension. Physical exam reveals flank tenderness, and a plain radiograph is unrevealing. Intravenous urography is obtained, and the results are shown in Figure A. Which of the following is most closely associated with the pathogenesis of this disorder?