Studies on Microscopic Features and Pathogensis of Idiopathic Ureteropelvic Junction Stricture

Hwang, Hyon Woo; Woo, Young Nam

Abstract

Idiopathic ureteropelvic junction stricture is not an uncommon disorder with resultant hydronephrosis of affecting kidney, and most frequently encountered in infant and children. Multiple causes of stricture have been identified. Abnormal organization of smooth muscle bundles at the ureteropelvic junction has been reported, and electron microscopy has demonstrated excessive collagen deposition within the intramural stroma. However, the exact cause of obstruction of UPJ stricture is uncertain. We reviewed 23 cases with idiopathic hydronephrosis underwent dismembered pyeloplasty. Examination of strictured segment with light the normal interwoven pattern, were arranged into an abundant outer circular and an inner longitudinal layer in 21 of 23 cases. But muscle thickness was not changed, and collagen was normal in both amount and arrangement. This results suggested that the abnormal muscle arrangement at the ureteropelvic junction might be the cause of the idiopathic stricture.