Case 23-2010

A 49-year-old man was admitted to this hospital because of perinephric collections of fluid and acute renal failure. Seven years earlier, routine testing revealed an elevated hematocrit; regular phlebotomy was begun. Ten months before admission to this hospital, dyspnea on exertion developed; imaging studies showed pleural effusions and bilateral perinephric cystic lesions. One month before admission, left-flank pain developed suddenly, and the left perinephric collection of fluid had enlarged; a drain was placed, and acute renal failure developed. A diagnostic procedure was performed.