Polyps in the exstrophic bladder. A cause for concern?

The role of environmental injury in carcinogenesis is widely recognized. Malignancy in exstrophic bladders has been reported most frequently in untreated adults and those undergoing surgical treatments which involve the mixing of fecal and urinary streams. The question of whether the closed exstrophic bladder has a similar potential for malignancy has not been resolved. The polypoid appearance of the exstrophic bladder template raises the concern of premalignant lesions. We characterized the histology of these lesions and analyzed their microscopic features with particular reference to predisposition for dysplasia. In doing so, we attempt to address the aforementioned question and set the stage for definitive quantification of the risk of malignancy in these patients with careful, long-term followup.

Under institutional board review, the slides of 38 patients with classic bladder exstrophy who had polyps excised at the time of closure were reviewed by a single genitourinary pathologist (JIE). The most common findings were reported for polyps resected at primary and secondary closure, respectively, and a comparative analysis was performed.

Of the 38 cases 24 were primary closures and 14 were secondary closures. Six of the primary closures were delayed by 6 weeks or greater. The 2 basic types of polyps observed were fibrotic and edematous. Both types were associated with overlying reactive squamous metaplasia in approximately 50% of cases. Varying degrees of fixed on file Brunn's nests, cystitis cystica and cystitis glandularis were noted. Cystitis glandularis was observed in a significantly greater percentage of secondary closures (p = 0.0014).

Although no dysplasia was noted, cystitis glandularis is associated with the development of adenocarcinoma of the bladder. The finding of cystitis glandularis suggests a more severe epithelial injury and it follows that the significant majority of these cases (10 of 14, 71.4%) were observed with polyps resected during secondary closure. These patients warrant future surveillance with urine cytology and cystoscopy as they enter adult life.