Urothelial Differences In The Exstrophy-Epispadias Complex: Potential Implications For Management

Purpose: The authors examined the urothelium of exstrophy-epispadias complex spectrum patients for histological differences and expression of terminal markers of urothelial differentiation.Materials and Methods: Between 2012 and 2017 bladder biopsies were obtained from 69 pediatric exstrophy-epispadias complex patients. These specimens were compared to bladder specimens from normal controls. All bladder specimens underwent histological assessment followed by immunohistochemical staining for uroplakin-II and p63. Expression levels of uroplakin-II and p63 were then assessed by a blinded pathologist.Results: Forty-three classic bladder exstrophy biopsies were obtained (10 newborn closures, 22 delayed closures, and 11 repeat closures). Additional biopsies from 18 cloacal exstrophy patients and 8 epispadias patients were also evaluated. These specimens were compared to 8 normal control bladder specimens. Overall, uroplakin-II expression was lower in exstrophy-epispadias complex patients compared to controls (p<0.0001). Among classic bladder exstrophy patients, there was reduced expression of uroplakin-II in the delayed and repeat closures in comparison to newborn closures (p=0.045). Expression of p63 was lower in patients with exstrophy-epispadias complex compared to controls (p<0.0001). Expression of p63 was similar among classic bladder exstrophy patients closed as newborns when compared to delayed or repeat closures. Classic bladder exstrophy patients had a higher rate of squamous metaplasia when compared to controls (p=0.044). Additionally, there was a higher rate of squamous metaplasia in the patients undergoing delayed closure in comparison to those closed in the newborn period (p<0.001).Conclusions: The urothelium in the exstrophy-epispadias complex bladder is strikingly different than that of healthy controls. Uroplakin-II expression is greatly reduced in exstrophy-epispadias complex bladders and is influenced by the timing of bladder closure. Reduced uroplakin-II expression and increased rates of squamous metaplasia in exstrophy-epispadias complex patients undergoing delayed closure suggests that exposure of the urothelium may induce these changes. These findings shed light on the molecular changes in exstrophy-epispadias complex bladders and may have implications on the appropriate timing of primary bladder closure, as those closed in the newborn period appear to have a greater potential for growth and differentiation.