Definition, Etiology, PathogenesisTop
Acquired cystic kidney disease refers to the presence of ≥4 cysts in each kidney in individuals with severe chronic kidney disease (CKD) caused by conditions other than polycystic kidney disease. It may develop in patients with CKD regardless of its cause and is particularly common in patients undergoing renal replacement therapy, with the incidence of cysts rising as dialysis vintage (length of time on dialysis) increases. Whilst etiology is unknown, proximal tubular cell proliferation is thought to be important. In the majority of cases cysts remain asymptomatic, but they may cause episodes of hematuria, chronic flank pain, or renal colic. In very rare cases, a cystic kidney may be palpable as an abdominal mass. In patients with CKD and acquired cystic kidney disease, the risk of cancer is significantly increased. The best estimate is a prevalence of at least 4%, although the true prevalence is probably higher. In 25% to 50% of cases, renal cancer is multifocal and bilateral.
Diagnosis is based on ultrasonography with computed tomography (CT) for any questionable lesions; given the higher prevalence of malignancy, in these patients the threshold for proceeding to CT should be lower. Definitive recommendations for periodic screening of long-vintage dialysis patients do not exist, although long-vintage patients with a long life expectancy are subjected to yearly ultrasonography in many centers.
There is no specific treatment unless symptoms or complications develop. Episodes of hematuria are treated symptomatically. Surgical treatment may be necessary in case of retroperitoneal bleeding from a cyst, persistent or severe hematuria, cyst infection not responding to medical treatment, and suspected or confirmed kidney cancer.