[Benign multilocular cystic nephroma versus cystic nephroblastoma. A review and classification of cystic metanephric neoplasms (author's transl)].

A review of reported cases of cystic metanephric tumors is given. It is shown that among these neoplasms two distinct pathologic entities exist: the cystic nephroblastoma and the benign multilocular cystic nephroma. The former, a benign variant of Wilms' tumor, is found in children of younger age. Its possible precursor is the infantile form of nephroblastomatosis. The second neoplasm, a clinically and biologically benign tumor, occurs in older children and in half of the cases it is also encountered in adults. It derives from metanephric hamartomas which have their origin in the huvenile form of nephroblastomatosis.