Wilms tumorlet, nodular renal blastema and multicystic renal dysplasia.

We reviewed 60 cases of multicystic renal dysplasia collected during a 10-year period. Differentiated nonproliferative nodular renal blastema occurred in 6.7 per cent of the cases, which is similar to the incidence of nodular renal blastema in kidneys of other infants with congenital obstructive uropathy. A unique case of cystic dysplasia containing nodular renal blastema and Wilms tumorlet indicates the possibility that a persistently proliferative nephroblastomatous lesion may rarely occur.