Abstract
Endometriosis is a common gynecological condition, but involvement of the urinary tract is rare. Ureteral endometriosis can present in a nonspecific fashion, and may mimic ureteral malignancy. This case report describes a 44-year-old woman who initially presented with chronic flank pain and was found to have left-sided renal dysfunction and a distal left ureteric mass. She was eventually diagnosed with ureteral endometriosis after undergoing nephroureterectomy for what was thought to be either a ureteral fibroepithelial polyp or transitional cell carcinoma. Ureteral endometriosis should be considered in the differential diagnosis for a woman presenting with obstructive uropathy in the presence of a ureteric mass.