Renal cell carcinoma arising in a regressed multicystic dysplastic kidney.

Controversy surrounds the management of multicystic dysplastic kidney. Recent advances in radiological imaging have resulted in a higher incidence of its detection, and they provide an accurate noninvasive means of diagnosis and followup. Consequently, the need for surgical removal of these lesions is being reevaluated. We report a case of renal cell carcinoma arising from solid renal dysplasia associated with a regressed multicystic dysplastic kidney. We emphasize the potential risk of nonoperative management of these lesions and further define the spectrum of malignant degeneration associated with renal dysplasia.