Primary malignant renal tumors in the second decade of life: Wilms tumor versus renal cell carcinoma.

Primary renal malignancies occur least frequently in the second decade of life. Of the 4,798 cases of renal cell carcinoma and Wilms tumor referred to the Armed Forces Institute of Pathology 53 renal cell carcinomas and 56 Wilms tumors occurred in the 10 to 20-year age group. Pathologically, both tumors in this age range are similar to those occurring at a more typical age, and histologic differentiation between renal cell carcinoma and Wilms tumor is seldom a problem. While radiographic evaluation is useful to characterize the neoplasm, evaluate the contralateral kidney and detect the presence of tumor extension, current imaging techniques cannot confidently distinguish these 2 tumors.