Zinner Syndrome: a rare congenital urogenital anomaly

Zinner syndrome (ZS) is a rare congenital anomaly of the urogenital tract, with an estimated incidence of 0.00214%,^1,2,3 arising from abnormal embryonic development of the distal mesonephric duct,⁴ occurring between the 4^th and 13^th weeks of gestation.^1,2,3,5 It is characterized by a triad of clinical manifestations: seminal vesicle cyst (SVC), ejaculatory duct obstruction and ipsilateral renal malformation, commonly presenting as kidney agenesis or multicystic dysplasic kidney (MCDK).^1,2,3,4,5
ZS is predominantly asymptomatic, with symptoms usually emerging after the onset of intense sexual activity^3,5 due to seminal fluid accumulation caused by ejaculatory duct stenosis.^1,2 Common symptoms are generally non-specific and include abdominal, pelvic and scrotal pain along with lower urinary tract symptoms.^1,2,3,4,5 Painful ejaculation and recurrent epididymitis have also been reported.⁴ Infertility is a concern in ZS, affecting approximately 45% of patients^1,2, primarily due to azoospermia.¹ Although the underlying pathogenesis remains unclear¹, it is speculated that unilateral testicular obstruction may lead to the production of anti-sperm antibodies.^1,2
Due to its asymptomatic nature and rarity, the diagnosis of ZS during the prepubertal period is mostly incidental, typically occurring during routine ultrasounds conducted to investigate abnormalities of kidney and urinary tract.³ MRI serves as the confirmatory diagnostic tool^1,3,4,5, offering superior resolution without the risks associated with radiation exposure.^3,5
Management of ZS generally involves a conservative approach with watchful waiting for asymptomatic or minimally symptomatic patients.^1,2,3 Surgical intervention is reserved for individuals exhibiting significant symptoms or those who have not responded to conservative treatment.^1,2,3 Annual follow-up with clinical and imagological evaluations is recommended for all patients.^1,2 Upon reaching adulthood, a semen analysis should be conducted to assess fertility status.^1,4
With the increasing use of ultrasound, there has been a rise in the detection of renal agenesis, MCDK and urinary tract malformations.³ Although these anomalies are common, they should prompt clinicians to consider associated genitourinary anomalies, such as SVC in male patients and, consequently, ZS,^2,3 since early detection and appropriate management are crucial in preventing its complications.⁴ While further studies are necessary to substantiate the benefits of early surgical intervention, timely excision of the affected duct may help prevent infertility and reduce the impact on the contralateral genitourinary tract.¹

References :

Hofmann A, Vauth F, Roesch WH. Zinner syndrome and infertility─a literature review based on a clinical case. Vol. 33, International Journal of Impotence Research. Springer Nature; 2021. p. 191-5. Cascini V, Renzo D Di, Guerriero V, Lauriti G, Chiesa PL. Zinner syndrome in pediatric age: Issues in the diagnosis and treatment of a rare malformation complex. Front Pediatr. 2019;7(APR). Lin CC, Sheu JC, Tsai PS, Lee MD, Lin TH, Tsai JD. Zinner syndrome in children: clinical presentation, imaging findings, diagnosis, and outcome. Pediatric Nephrology. 2022 Dec 1;37(12):3075-84. Kumar S, G KI, Khalil-Khan A, Arul Pitchai ADP, Sathiamoorthy R, Raju E. Zinner Syndrome. Cureus. 2022 Nov 10; Ghonge NP, Aggarwal B, Sahu AK. Zinner syndrome: A unique triad of mesonephric duct abnormalities as an unusual cause of urinary symptoms in late adolescence. Indian Journal of Urology. 2010 Jul;26(3):444-7.