[Nephroblastomatosis and its relation to Wilms' tumor].

A group of 18 cases of nephroblastomatosis (NBM) was separated during an analysis of 188 renal tumours in childhood. NBM occurred associated with only Wilms' tumours (total 171 cases). NBM was classified according to a scheme of the "National Wilms' Tumor Study". Perilobar form was found in 5 cases, intralobar in 9, combined in 4 cases. Median age of all the patients suffering from NBM was close to that of the whole group of Wilms' tumours (37.4 months compared with 44.3 months). Medium age in the time of diagnosis of nephroblastoma with intralobar nephroblastomatosis was 28.3 months, i.e. by 16 months lower than the whole group of Wilms' tumours. The most frequent form of NBM consisted of mature tubular hamartomas or looked like renal basophilic adenomas. A blastemic component was less frequent and, in intralobar NBM, could not be distinguished reliably from blastemic structures in nephroblastoma. NBM could be distinguished even in necrotic tumours irradiated before the operation. NBM occurred in 5 of 8 bilateral nephroblastomas and in majority of primary multinodular tumours (63 percent). Relation of NBM to the development of Wilms' tumour is close but its value for pathogenesis cannot be proved unequivocally by morphology. Considering a high rate of bilateral NBM its finding in a kidney with Wilms' tumour necessitates regular checking of opposite kidney for early development of metachronic bilateral nephroblastoma.