the authors present a case of congenital bladder diverticulum and a benign inflammatory bladder wall lesion mimicking bladder rhabdomyosarcoma . renal tract ultrasonography revealed a large right - sided bladder diverticulum and a 2.2 x 1.3 x 3.6 cm lobulated thickening on the posterior bladder wall , which was associated with increased vascularity on doppler imaging ( figure 1 ) . ultrasound images demonstrating a large bladder diverticulum the diverticulum was clearly seen on micturating cystourethrogram ( mcug ) . subsequent magnetic resonance imaging ( mri ) scan confirmed the presence of a large bladder diverticulum and also demonstrated an enhancing , irregular , nodular posterior bladder wall thickening which was confined to the bladder . cystoscopy revealed a papillary lesion on the posterior bladder wall adjacent to the diverticulum opening ( figure 2 ) . ultrasound images demonstrating a posterior bladder wall lesion with increased vascularity the cystoscopic appearances resembled a rhabdomyosarcoma . diverticulectomy and ureteric re - implantation were performed to resolve bladder outlet obstruction and an open bladder biopsy of the lesion was conducted at the same time . the patient made an uneventful recovery and continues to do well with no further episodes of urine retention at outpatient review . congenital bladder diverticula in children are uncommon and rarely cause bladder outlet obstruction ( 12 ) . benign inflammatory lesions can mimic rhabdomyosarcomas both radiologically and macroscopically as in the present case ( 3 ) . corbett et al reported an identical case of congenital bladder diverticulum co - existing with a benign lesion resembling a tumour ( 4 ) . based on the present case and the case reported by corbett et al , the authors postulate that benign inflammatory lesions mimicking tumours occur with congenital bladder diverticula but due to their transient nature are not frequently reported . in cases where dual pathology of bladder wall lesions and diverticula are observed , clinicians can be reassured that this is probably a benign process .
congenital bladder diverticula in children are uncommon and rarely present with bladder outlet obstruction . 
 we present a case highlighting an interesting association between a congenital bladder diverticulum and a benign inflammatory bladder wall lesion mimicking a rhabdomyosarcoma . 
 open surgery was required as different imaging modalities and cystoscopy were insufficient to exclude a malignant process .