[Cancer of the kidney mimicking renal multilocular cyst]

Two cases of multilocular cystic adenocarcinoma of the kidney are presented. Although ultrasonography (US) and x-ray computed tomography (CT) are generally considered to be excellent diagnostic methods for renal cystic lesions, in the 2 cases reported here they failed to give the correct diagnosis. These unusual cases altered us to the possibility that the capabilities of modern diagnostic imaging techniques can lead to a false sense of security regarding the prognosis. To our knowledge, there are no reliable clinical features which distinguish multilocular cystic adenocarcinoma from multilocular cystic nephroma.