Acquired cystic kidney disease.

ACKD is characterized by the development of many fluid-filled renal cysts and sometimes neoplasms in the kidneys of individuals with chronic renal failure but without a history of hereditary cystic disease. The condition is seen mainly in dialysis patients, but often begins in patients with ESRD before dialysis is started. Most patients with ACKD are asymptomatic, but the disorder may be associated with such serious complications as retroperitoneal hemorrhage and metastatic renal cell carcinoma. The diagnosis of ACKD and its complications is best achieved by CT scanning, although US and MR imaging may be useful in evaluation, particularly in patients not treated with dialysis. Cyst hemorrhage is common in ACKD and may cause flank pain and hematuria. Hemorrhagic cysts may be recognized by their CT scan, sonographic, or MR imaging features. Hemorrhagic cysts may rupture into the perinephric space causing large perinephric hematomas. These can usually be treated-conservatively. Patients with ACKD, particularly those treated with dialysis, have an increased risk of renal cell carcinoma. Renal cell carcinoma may also develop in the native kidneys of renal transplant recipients with good graft function many years after transplantation. Annual imaging of the native kidneys of all dialysis patients or of transplant recipients for the development of carcinoma is not justified, however, because it has not been shown to have a significant effect on patient outcome. Screening may, however, be useful in selected dialysis patients with good general medical condition and who have known risk factors for renal cell carcinoma including prolonged dialysis, large kidneys, ACKD, and male gender. Screening of the native kidneys of transplant recipients may be performed when they are referred for US evaluation of the renal allograft.