Bilateral Native Kidney Papillary Renal Cell Carcinomas in a 11-Year-Old Renal Transplant Patient.

Renal cell carcinomas (RCCs) are the most common renal tumors in adults and are usually sporadic and unilateral. Renal transplant recipients have an increased risk of developing RCC. RCC development after kidney transplantation is very rarely reported in children. We present a 11-year-old boy who had cadaveric kidney transplantation for kidney failure 2 years ago. He was under immunosuppressive therapy and presented with microscopic hematuria. An ultrasound (US) revealed bilateral solid renal masses. Further cross-sectional imaging showed a 60 × 70 × 60-mm right renal mass with claw sign and a 5 × 6 × 6-mm mass in the left renal lower pole. A bilateral radical nephroureterectomy of native kidneys was performed. The pathology revealed bilateral papillary RCC without TFE3 upregulation. The patient was kept on low-dose immunosuppressive therapy in the perioperative period. He received no chemotherapy but a close radiological surveillance was undertaken. He is tumor-free 2 years after the operation. RCC is a rare tumor for children and bilateralism is even rarer. The child had a history of chronic kidney disease, peritoneal dialysis, and immunosuppressive therapy. As there are no standardized protocols regarding imaging in transplanted kidneys routine surveillance, US follow-up should also focus on detecting malignancy.