Zinner’s syndrome in two young middle-aged men: a case report and review of the literature

Abstract

Zinner syndrome (ZS) is a relatively uncommon congenital genitourinary malformation, characterised by a triad of conditions: unilateral renal hypoplasia or dysplasia, ipsilateral ejaculatory duct obstruction and seminal vesicle cysts. This association is caused by the hypoplasia of the distal portion of the Wolffian duct between the 4th and 13th week of gestational age. To date, approximately 221 cases have been documented, the majority of which are case reports, with only a few being retrospective studies. However, the number of cases remains relatively limited. The lack of a clear and consistent set of symptoms can result in misdiagnosis. This paper presents two patients with two different presentations of Zinner syndrome.

Clinical trial number: Not applicable.

Introduction

Zinner syndrome (ZS) is a rare congenital disorder characterised by the presence of cystic seminal vesicle and ejaculatory duct obstruction, which is associated with ipsilateral renal hypoplasia [1]. The symptoms of ZS are typically nonspecific and may include perineal pain, discomfort, dysuria, dyspareunia, epididymitis, painful ejaculation, and haemospermia. The most significant symptom is its potential to cause infertility in up to 45% of cases, which is known as azoospermia [2]. ZS is typically diagnosed in individuals in their 30–40 s. However, diagnosing asymptomatic patients may present diagnostic challenges, whereas diagnosing symptomatic patients is relatively straightforward. Ultrasound is frequently the preferred diagnostic modality, with magnetic resonance imaging (MRI) and computed tomography scans often providing supplementary information. The standard surgical treatment is transurethral vesiculectomy or ejaculatory duct resection. This report presents two cases of Zinner’s syndrome treated with transurethral or robotic surgery, with differing clinical presentations.

Case presentation

Case 1

A 28-year-old married patient presented to our hospital with a nine-month history of perineal discomfort and painful urination. No abnormalities were identified in the patient’s past medical history or in the results of the tests conducted. Additionally, a palpable left seminal vesicle mass was observed during rectal examination. A rectal ultrasound revealed the presence of a cystic space measuring 3.59 × 2.95 cm in the left seminal vesicle, accompanied by epididymitis. Abdominal CT revealed the absence of the left kidney and cystic occupation of the left seminal vesicle gland with protrusion into the bladder (Fig. 1A-C). A pelvic MRI revealed the presence of multiple short T1 and short T2 cystic columnar abnormal signal shadows in the left seminal vesicle region. These shadows exhibited low signal on DWI, with clear boundaries. The largest of these shadows measured 2.9 cm × 4.2 cm, and no obvious enhancement was observed. A long T1 and long T2 abnormal signal shadow of approximately 1.7 cm × 2.2 cm × 2.7 cm was observed in the left medial anterior aspect of the psoas major muscle (at the level of the umbilicus), with distinct borders (Fig. 1D-F). In light of these observations, a diagnosis of Zinner syndrome was formulated.

Fig. 1

Enhanced CT. Coronal CT (A) shows left renal hypoplasia, right renal hypertrophy and a left anomalous ureter. Axial (B) and sagittal (C) views demonstrate cyst protrusion into the bladder. MRI: Coronal (D) and sagittal (F) MRI reveal a left seminal vesicle cyst. This dilated cystic structure extends into the bladder (D, E, F)

Following the patient’s consent, a robot-assisted vesicourethral cystectomy via a laparoscopic approach was undertaken. During the procedure, we confirmed the dilatation of the left seminal vesicle and vas deferens. The robot-assisted cystectomy was completed without intraoperative complications like adjacent organ injury or significant bleeding. A pathological examination of the surgical specimen revealed that it exhibited features consistent with those of a seminal vesicle glandular cyst.Postoperatively, the patient reported complete resolution of perineal discomfort and painful urination. And Long-term follow-up over three years demonstrated sustained clinical improvement. Notably, a semen analysis performed at the 2-year follow-up revealed normal parameters, presented in Table 1.

Table 1

Case 2

A 25-year-old male was initially presented to our department on January 7th, 2021 following a two-year period of cohabitation with his partner, during which time he had not used appropriate contraceptive measures. He was diagnosed with azoospermia and found to be infertile. Based on previous diagnostic experience, a whole abdomen CT was initially performed, which revealed that the left kidney was not visible and a mass of sickly hyperdense shadow, measuring approximately 4.25 cm in length, was observed on the left side of the pelvis, which was poorly demarcated from the left seminal vesicle glands (see Figs. 2A-D). A pelvic MRI revealed bilateral seminal vesicle glands with full morphology and short T1 and short T2 signals. Additionally, the examination showed thickened and tortuous ducts on the left side of the seminal vesicles, a dilated vas deferens on the left side of the vas deferens (2.4 cm wide at its widest point), and heterogeneous signals of the epididymis on the right side (FIGURE 2E-H). Though digital rectal examination (DRE) revealed no palpable masses in the seminal vesicles or prostate, these findings were consistent with a diagnosis of Zinner syndrome. Given the patient’s clinical discomfort and infertility, a transurethral ejaculatory vasectomy was eventually performed. Postoperative pathology also confirmed the presence of only cystic tissue.

Fig. 2

Enhanced CT. Coronal images (A) demonstrated left renal hypoplasia and right renal hypertrophy. Axial images (B) revealed a mass-like hyperdense shadow on the left side of the pelvis. Sagittal images (C-D) shows the large shadow poorly demarcated from the left seminal vesicle glands. Magnetic resonance imaging (MRI): The coronal (E) and sagittal (F) images demonstrated the presence of bilateral seminal vesicle glands with full morphology. The images revealed a thickened and tortuous left seminal vas deferens and uneven signals in the right epididymis(G-H)

Given the potential impact of ZS on male fertility, the patient sought a semen analysis following the procedure. The results of the in vitro semen analysis are presented in Table 2. The laboratory results for FSH, LH, prolactin and free testosterone were within the normal range, and the examination of the Y chromosome (Y gene 1/2/3, AZFa/b/c) was unremarkable. Notwithstanding the amelioration of symptoms, the patient recognised the potential for infertility to persist. Consequently, he elected to pursue assisted reproductive technology. After a period of six months, these endeavours proved successful, resulting in a pregnancy with his partner, which engendered profound relief and elation.

Table 2

Discussion

Zinner syndrome, a triad of renal hypoplasia associated with ipsilateral seminal vesicle cysts and ejaculatory duct obstruction, was initially delineated by Zinner in 1914 [1]. Due to the non-specific or non-severe nature of its symptoms, ZS is typically diagnosed during the reproductive years, between the ages of 20 and 40. In particular, it has been observed that patients typically remain asymptomatic until the seminal vesicle cyst reaches or exceeds 5 cm in size. Cysts of a greater size may result in inflammation of the urinary tract, exert a dominant effect on surrounding organs, or become inflamed or infected. The prevalence of Zinner syndrome was determined to be 214 per 100,000 patients in a study conducted by Sheih et al [2]. Case 1, a 28-year-old male, presented with prominent perineal discomfort and dysuria despite a relatively small seminal vesicle cyst (3.59 × 2.95 cm). This contrasts with prior reports suggesting symptom onset primarily occurs with cysts ≥ 5 cm, indicating that clinical discomfort may arise independently of cyst size.

The majority of cases thus far have been found to involve abnormalities of the left kidney, seminal vesicle, and ejaculatory duct. Van den Ouden [3] et al. conducted a comprehensive analysis of the most common symptoms associated with Zinner’s syndrome. A total of 52 patients with Zinner syndrome were studied, and the most common symptoms were identified as dysuria (37%), dyspareunia (33%), perineal pain (29%), epididymitis (27%), post-ejaculatory pain (21%), and scrotal pain (13%). It has been observed that the majority of cysts can be felt through rectal examination alone [3]. Case 2, a 25-year-old male, presented with infertility as the sole complaint, devoid of urinary symptoms. This asymptomatic profile conflicts with literature documenting dysuria or pelvic pain in most of ZS patients, underscoring the syndrome’s capacity for silent reproductive dysfunction. Notably, both cases exhibited left renal agenesis and seminal vesicle cysts, yet diverged radically in symptomatology—a pattern scarcely addressed in existing ZS classifications.

Although DRE in this case did not reveal a palpable seminal vesicle mass, it remains a critical initial screening tool for evaluating pelvic pathology. In Zinner syndrome, cysts may be small or deeply situated, limiting their detection via physical examination. The absence of palpable abnormalities on DRE underscores the necessity of advanced imaging for definitive diagnosis, particularly in patients with unexplained infertility or subtle symptoms. The most appropriate diagnostic method is transabdominal ultrasound, as it is non-invasive, the examination is inexpensive, and it does not entail radiation exposure [4]. The most common ultrasound finding is an anechoic mass in the region of the seminal vesicles.

However, ultrasound is an operator-dependent method, and the results are subjective. A definitive diagnosis should therefore be made by CT and MRI. While MRI is the gold standard for delineating seminal vesicle cysts and soft-tissue relationships in Zinner syndrome, CT retains critical utility in the diagnostic workflow, which rapidly confirms ipsilateral renal agenesis—a hallmark of ZS. Besides, for patients with contraindications to MRI (e.g., metallic implants) or limited access to advanced imaging, CT provides a pragmatic alternative for initial anatomical assessment.Typical CT findings are the presence of a cystic mass around the periprostatic area behind the bladder with ipsilateral renal hypoplasia.

MRI can be used as a diagnostic gold standard, not only to make a definitive diagnosis, but also to determine surgical planning for the removal of the seminal vesicle cysts [5]. The typical findings on MRI are the paracentral and periprostatic localisations of seminal vesicle cysts with variable signal intensities in the T1-weighted images, and the periampullary localisation in the T2-weighted images. The signal intensity on T1-weighted images is low, while that on T2-weighted images is high. In conclusion, imaging remains a crucial element in the diagnosis of ZS, with CT and MRI being the most accurate imaging modalities for evaluating the genitourinary system.

Our study is limited by its small sample size. However, the stark contrast between Cases 1 and 2 highlights the need for phenotype-specific diagnostic criteria. Multicenter registries should explore whether clinical subtypes correlate with distinct embryological defects or cyst characteristics.

The differential diagnosis of ZS includes several cystic diseases of the pelvic organs, i.e., vesicoureteral diverticulum, prostatic cysts, ejaculatory cysts, ureteral bulges, and abscesses. Indeed, the location of the cyst and associated developmental abnormalities, such as renal hypoplasia or external genital malformations, play a crucial role in confirming the diagnosis of ZS.

In terms of treatment, asymptomatic patients are typically advised to undergo observation and regular follow-up. The treatment of patients with ZS typically involves transurethral resection of seminal vesicle cysts and ejaculatory ducts, in addition to laparoscopic surgery. The present evidence suggests that laparoscopic surgery, or robotic-assisted laparoscopic surgery, is the most common surgical method. The application of robotic assistance in laparoscopic surgery has gained traction for complex genitourinary reconstructions, particularly in anatomically challenging cases like Zinner syndrome. In Case 1, robot-assisted laparoscopic cystectomy allowed precise dissection of the seminal vesicle cyst while preserving adjacent neurovascular structures—a critical advantage highlighted in recent studies. For an instance, Talwar et al. (2021) reported a case of Zinner syndrome presenting with hematuria managed by robot-assisted laparoscopic cystectomy, demonstrating precise excision of a large seminal vesicle cyst containing sharp stones, with a console time of 110 min and minimal intraoperative blood loss. Postoperative recovery was uneventful, and the patient remained symptom-free at 6-month follow-up, highlighting the robotic platform’s efficacy in addressing anatomically complex and rare presentations of ZS through enhanced visualization and minimally invasive precision [6].

However, the efficacy of these surgical methods in addressing infertility remains limited. Consequently, assisted reproductive technologies are being considered as the primary strategy for achieving fertility in these patients.

The precise mechanism through which ZS induces infertility remains to be fully elucidated. Some scholars have proposed a connection with oligospermia or azoospermia, whilst others have suggested that ejaculatory duct obstruction may result in the production of antisperm antibodies or other inhibitory factors. In any case, the majority of patients do not conceive naturally after treatment and often resort to assisted reproductive techniques.