Botryoid Wilms Tumor in a 2-Year-old Boy: A Case Report.

We report a case of botryoid Wilms tumor that occupied the renal pelvis. A 2-year-old boy was referred to us with a chief complaint of macrohematuria. Ultrasonography, computed tomography, and magnetic resonance imaging showed a tumor occupying the left renal pelvis. Radical nephroureterectomy was performed. The resected specimen showed a botryoid sarcoma-like appearance, with a pedicle attaching to the pelvicalyceal wall, occupying the left renal pelvis. Histologic findings confirmed botryoid Wilms tumor. Postoperative adjuvant chemotherapy was executed. There was no recurrence or metastasis 6 months after nephroureterectomy.