Pediatric Zinner syndrome variants: Case series with newer insights into pathogenesis in early childhood

Zinner Syndrome (ZS) is a rare congenital disorder characterized by seminal vesicle cysts (SVC) and ipsilateral upper urinary tract abnormalities, mainly due to developmental anomalies of the mesonephric duct. This series highlights our institutional experience with pediatric ZS, with a review of the current literature offering insights into its etiopathogenesis in early childhood.

A retrospective case review of pediatric ZS diagnosed at our institution from 2019 to 2023, alongside a comprehensive literature review.

Four pediatric ZS cases were identified, a neonate, an infant and two older (pre-pubertal) children, presenting with recurrent epididymo-orchitis and/or UTIs. The two older children had duplex systems, both undergoing curative upper moiety heminephrectomy; the infant underwent nephroureterectomy and the neonate is under observation, asymptomatic for past 18 months.

When Zinner identified the link between unilateral renal agenesis and ipsilateral SVC in 1914, the condition's embryological basis was attributed to incorrect ureteric bud migration from the mesonephric duct, failing to stimulate the metanephros, leading to renal agenesis/dysplasia and this disruption was hypothesized to obstruct seminal vesicle drainage, causing cyst formation. Another theory suggests anomalous development of the distal mesonephric duct leading to ejaculatory duct atresia/stenosis which results in cystic enlargement of the seminal vesicles which, in turn, leads to aberrant ureteral budding, resulting in renal malformations. It is our belief that the SVCs, that are typically problematic in adolescence/adulthood due to secretion accumulation, sometimes manifest in childhood due to urinary reflux into the seminal vesicles, leading to epididymo-orchitis or UTIs. This contrasts with adult pathogenesis, where ejaculatory duct obstruction predominates. Hence, treatment leans towards a conservative approach for asymptomatic cases, with surgery reserved for symptomatic children. The scope of this case series is limited by the rare nature of ZS in prepubertal children (41 published cases in English literature), preventing a comprehensive understanding of its untreated natural history and restricting the formulation of generalized recommendations.

The variability in presentation of ZS in children necessitates a tailored approach. Unlike adults, where ejaculatory duct obstruction is the common cause, pediatric ZS symptoms mainly stem from urethra-cystic reflux, leading to recurrent infections.