Pyelonephritis complicating relapsing acute pancreatitis.

A case of right pyelonephritis with hydronephrosis complicating relapsing acute pancreatitis and right pararenal phlegmon formation is presented. Hydronephrosis is a reportedly rare complication of extrapancreatic inflammation; the only 6 previous cases involving the right side are reviewed. The present case report, to our knowledge, is the first to describe clinical and laboratory evidence of pyelonephritis secondary to partial obstruction of the right upper renal tract by an extrapancreatic phlegmon. The clinician caring for patients with acute pancreatitis should be aware of this important complication, since the presentation of pyelonephritis-flank pain and fever--could erroneously be attributable solely to the pancreatitis.