Renal cell carcinoma in children with diffuse cystic hyperplasia of the kidneys

We report the clinical, pathologic, and genetic features of renal malignanc y in two children with diffuse cystic hyperplasia. Both presented with mass ive bilateral nephromegaly. Neither had a family history or clinical findin gs suggestive of tuberous sclerosis or von Hippel-Lindau disease. The kidne ys of both children were extensively replaced by tubulocystic hyperplasia w ith large eosinophilic epithelial cells. The masses of hyperplastic tissue were nodular, compressing remnants of uninvolved renal parenchyma. Tubulopa pillary carcinoma was present in both children, one of whom had bilateral m ulticentric carcinoma. No loss of heterozygosity was detected in the tumors at the TSC1, TSC2, or VHL gene regions, and no alterations in the VHL gene were detected using single-strand conformation polymorphism analysis. Thes e cases of bilateral renal enlargement with diffuse cystic hyperplasia appe ar to represent a new clinical syndrome that may warrant bilateral nephrect omy because of the risk of malignancy.