[Partially differentiated cystic nephroblastoma].

Two new cases of cystic partially differentiated nephroblastoma, which were treated by nephrectomy, are reported. Their gross appearance is undistinguishable from a multilocular cyst, with the only difference being the presence of buds of blastema within the cystic septa. While cystic partially differentiated nephroblastoma as well as multilocular cyst have never been reported to be associated with local or metastatic recurrence and therefore their treatment consists of simple nephrectomy, the presence of blastema suggests a differentiates stage of Wilms' tumor, thus demanding a close surveillance of the patient.