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Renal cell carcinoma: unusual pediatric renal tumors.

Renal cell carcinoma (RCC), the most common renal tumor in adults, is rare in childhood, with an incidence much lower than that of Wilms' tumor. It is initially asymptomatic, but clinically overt symptoms such as an abdominal mass or hematuria may indicate late-stage disease and a poor prognosis. In this report, we describe the imaging features of pediatric RCC and emphasize the value of early diagnosis offered by ultrasonographic screening. From 1989 through 1997, we encountered five children (aged 7-15 yr) with RCC. Of these, two presented with symptoms, while the other three were asymptomatic and were identified in a large, school-based urologic ultrasonographic survey, in which more than 800,000 children were screened by our team. Reviewing the imaging features, we found that four tumors exhibited a heterogeneous nature. One patient had bilateral well-defined homogeneous tumors, which proved to be bilateral low-grade RCC. The three asymptomatic patients had smaller tumors than the other two patients. These three were treated with nephrectomy and were well after at least 15 months of follow-up. The two patients who presented with symptoms eventually died of tumor recurrence and pulmonary metastasis, respectively. The findings in these five cases of pediatric RCC add knowledge regarding the imaging features of this disease and highlight the value of ultrasonographic screening for early diagnosis.