Sequential bilateral nephroblastic tumors of different cell types in an infant. Possible effect of chemotherapy versus de novo origin

A 14-month-old infant had a classical Wilms' tumor of the left kidney and subsequently developed a tumor showing predominantly mature mesenchymal elements and lack of cellular atypia in the right kidney. His father had classical Wilms' tumor of the left kidney. The various possibilities regarding the precise nature and mechanism of the development of the tumor in the right kidney are discussed. The similarities and the differences between this tumor and congenital mesoblastic nephroma are noted. The possible relation of chemotherapy to mesenchymal differentiation and maturation in Wilms' tumor is considered. The possibility of an unusual, histologically benign, mesenchymal variant in the spectrum of infantile nephroblastic neoplasia is also suggested.