Benign mesodermal polyp in childhood.

A ureteral fibrous polyp presenting as ureteropelvic junction obstruction in a 10-year-old boy is reported. These neoplasms are uncommon, especially in children. If a salvageable kidney is present, resection of the tumor and adjacent ureter is proper therapy. However, in the present case the fibrous polyp had produced marked ureteropelvic junction obstruction, resulting in only a thin shell of renal parenchymal tissue, and therefore, nephroureterectomy was performed.