Ureteropelvic Junction Obstruction by a Long Intraluminal Polyp and a Concurrent Crossing Vein in a Symptomatic 8-Year-old Child.

Ureteropelvic junction obstruction due to intrinsic causes is often diagnosed antenatally during routine ultrasonography. Cases of extrinsic obstruction often present later and symptomatically, during childhood. We describe the rare case of an 8-year-old boy with a 2-day history of severe left flank pain, no fevers, and Society of Fetal Urology grade 3 hydronephrosis on ultrasonography. Laparoscopic dismembered pyeloplasty revealed a left ureteropelvic junction obstruction secondary to a large fibroepithelial polyp in the proximal ureter with a concomitant anterior crossing vein. We also provide a focused review of the pertinent published literature.