A 26-year-old male patient presented with abdominal pain attributed to small calculi located in the right lower ureter. A color Doppler ultrasound examination of the urinary system revealed ZS, indicating the presence of a posterior cystic mass in the prostate and the absence of the left kidney. The patient reported a regular sexual history spanning five years, during which he employed the coitus interruptus method for contraception. Over the past year, there has been a gradual decrease in ejaculatory volume, with the semen appearing clear. In the preceding month, only a minimal amount of transparent fluid was emitted during sexual intercourse.Ejaculation occurred without evident pain or discomfort, and no blood was detected in the seminal fluid. The patient reported no urinary discomfort; however, he experienced a sensation of incomplete defecation accompanied by mild anal distension. His medical records indicated no history of cryptorchidism, delayed pubertal development, or scrotal-perineal discomfort. He denied any family history of related conditions or previous surgical interventions. Bilateral testicular development was normal, although there was mild expansion of the bilateral epididymis and vasa deferentia. A digital rectal examination identified a cystic mass, with no tenderness detected in the prostate region. Two semen analyses confirmed absolute azoospermia, with semen volume ranging from 0.1 to 0.2 ml. The concentrations of neutral alpha-glucosidase, citric acid, fructose, and zinc were measured at 0.06 mU/time, 8.42 µmol/time, 0.05 g/L, and 4.59 mmol/L, respectively. A scrotal ultrasound examination indicated a left testicular volume of 10.1 mL and a right testicular volume of 10.4 mL. Peripheral blood karyotype analysis demonstrated a 46,XY chromosomal pattern. The sex hormone profile was as follows: estradiol (E2) at 126 pmol/L, luteinizing hormone (LH) at 6.14 IU/L, testosterone at 17.7 nmol/L, prolactin at 586 mIU/L, and follicle-stimulating hormone (FSH) at 6.44 IU/L. Abdominal magnetic resonance imaging and magnetic resonance urography (MRI/MRU) revealed the absence of the left kidney and left ureter (Fig. 1A). Additionally, a round cystic lesion was observed in the posterior aspect of the prostate gland and seminal vesicle.The lesion exhibited a uniform signal, with no enhancement observed on the contrast-enhanced scan, and its boundary appeared well-defined. The lesion measured 5.9 × 6.2 × 5.0 cm (Fig. 1B). However, the demarcation between the leading edge of the lesion and the seminal vesicle was indistinct, with notable compression of the proximal ejaculatory duct (Fig. 1C). Clinically, the diagnosis suggested Zinner syndrome (ZS) with azoospermia. The azoospermia was attributed to the compression of the seminal vesicle cyst on an otherwise healthy ejaculatory duct. Nonetheless, intraoperative findings did not corroborate our preoperative assessment.

Following comprehensive communication with the patient and his family, they opted for surgical intervention. The surgical procedures undertaken included endoscopic examination via seminal vesicle endoscopy and cystoscopy, retrograde catheterization of the right ureter, and laparoscopic cyst resection. Cystoscopy revealed a smooth urethral mucosal surface with no significant hyperplasia of the mass, which was visible on both sides of the verumontanum submucosa, exhibiting suspicious black punctate pigmentation (Fig. 1D). Notably, no bilateral ejaculatory duct openings were observed upon increased water pressure.The bladder neck was positioned slightly higher, and there was a noticeable elevation in the trigone region of the bladder. The right ureteral orifice was clearly visible; however, the left ureteral orifice could not be identified (Fig. 1E). The mucous membrane of the bladder wall appeared smooth. A right external ureteral stent was placed during the procedure to prevent inadvertent injury while excising the cyst. Laparoscopic examination revealed a raised cystic mass located inferior to the bladder, with both vasa deferentia appearing normal, although the right vas deferens was slightly dilated.The cyst’s surface was meticulously dissected from its base, ensuring the preservation of the bilateral vascular and neural structures. The dimensions of the cyst were 5 × 5 × 6 cm, with the bilateral vasa deferentia converging into the cyst from the left and right anterolateral aspects (Fig. 1F). The cyst’s base appeared to originate from the ampullae of the bilateral vasa deferentia. Palpation revealed that the left seminal vesicle was significantly atrophied (Fig. 1G), while the right seminal vesicle was not accessible. The right lateral wall of the cyst exhibited a focal patch-like structure resembling seminal vesicle tissue, which had fused with the cystic wall, rendering separation unfeasible (Fig. 1H). Approximately 100 ml of yellowish-brown, cloudy, and viscous fluid was aspirated from the sac using a needle.

Subsequent routine semen and seminal plasma biochemical analyses revealed a substantial presence of non-viable spermatozoa, accompanied by elevated α-glucosidase enzyme activity (3,358.80 mU/time), a normal citric acid concentration, and a negative result for fructose.The cyst was dissected in a longitudinal manner, revealing a thicker cyst wall, while the base was not examined upon opening. On the right side of the cystic cavity, focal and patch-like structures were observed, which had fused with the cystic wall and were inseparable from it. The bilateral vasa deferentia converged into the cyst, which lacked any additional openings (Fig. 1I-J). The typical periampullary structure of the bilateral vasa deferentia was absent, consistent with the patient’s bilateral ejaculatory duct obstruction.This cyst was not a seminal vesicle cyst resulting from unilateral obstruction of the ejaculatory duct, as is characteristic of Zinner syndrome (ZS). Instead, it was identified as an ejaculatory duct cyst formed by the fusion of the two ducts. The absence of seminal vesicle fluid in the cystic fluid impeded semen liquefaction and sperm activation. Consequently, natural conception was not feasible despite treatment efforts. Therefore, it was decided to resect the cyst and perform a left seminal vesiculotomy along with a bilateral vasectomy. Methylene blue was administered into the proximal vas deferens on both sides of the postoperative specimens, verifying that the orifices of both vas deferens were situated within the cysts, with no additional openings identified within the cysts (Fig. 1K-L). Consequently, the patient’s bilateral ejaculatory ducts coalesce to form an ejaculatory duct cyst lacking an outlet, ultimately resulting in azoospermia.

Two tissue specimens were submitted for postoperative pathological examination (Fig. 1M-N). The first specimen comprised capsular wall tissue, where the majority of the inner capsule wall lacked epithelial lining; however, a localized region exhibited columnar epithelium coverage, alongside a minor presence of atrophic seminal vesicle tissue adjacent to the cyst wall. Notably, the absent right seminal vesicle was identified within the right lateral wall of the cyst. The second specimen consisted of free seminal vesicle tissue.Postoperative pathological analysis corroborated the intraoperative findings. The patient experienced an immediate restoration of erectile function following the surgical procedure and resumed his preoperative sexual activity level after one month of follow-up. Over a six-month follow-up period, the patient reported no symptoms of discomfort. His erectile function remained normal, and he maintained the same level of sexual activity and satisfaction as prior to the surgery, although he noted a reduced volume of clear fluid in his ejaculate.

A: Coronal T2 MRI: The left kidney and left ureter were absent (red arrow); B: sagittal view T2 MRI: the round cystic lesion (red arrow); the bladder (yellow arrow); C: axial T2 MRI: the round cystic lesion (red arrow); the bladder (yellow arrow); the left seminal vesicle can only be seen at this level and it had diminished in size (blue arrow); D: The melanin deposits on both sides of the verumonis (red arrow); E: The left ureteral orifice could not be explored (blue arrow); F-H: ①The bladder, ②cyst, ③the right vas deferens,④ the left vas deferens, ⑤the left shrunken seminal vesicle, ⑥which was similar to the seminal vesicle structure on the right side wall of the cyst; I-J: ①The bladder, ②the cyst was empty,③ the left vas deferens, ④the right vas deferens, ⑤the cyst was opened with no visible exit; K-L: Methylene blue was injected into both sides of the proximal vas deferens and methylene blue was seen draining from the inner surface of the cyst (yellow circle); M-N: Postoperative pathology. A: Gross specimen; B: cyst wall (black arrow). A small amount of atrophied seminal vesicle tissue was observed in the focal area around the cyst wall (red circle)

This case study delineates three uncommon variations of Zinner syndrome: atrophy of the left seminal vesicle accompanied by the absence of the ipsilateral kidney and ureter, an underdeveloped right seminal vesicle adhered to the cyst wall, and fused ejaculatory ducts forming a singular cyst. While individual anomalies similar to these have been reported in the literature [3,4,5], the concurrent presence of these three variations has not been previously documented, indicating a potentially unique variant of Zinner syndrome.

The exact mechanism through which ZS leads to infertility is not yet fully understood [6]. Certain studies associate it with oligospermia or azoospermia [7], whereas others propose that obstruction of the ejaculatory duct may induce the production of anti-sperm antibodies or other inhibitory factors [8,9,10,11]. Although deferento-vesiculography (DVG) was previously considered the diagnostic gold standard [12–13], its use has declined due to its invasive nature; instead, enhanced computed tomography (CT) and magnetic resonance imaging (MRI) are now more commonly employed [14, 15].

Various treatment modalities, including transurethral resection of the ejaculatory duct (TURED), have demonstrated variable outcomes. Some studies report enhancements in semen quality and increased pregnancy rates [16, 17], whereas others emphasize the occurrence of complications such as urinary and ejaculatory dysfunction [18]. Alternative interventions, such as open surgery, laparoscopic, and robotic techniques, have been investigated [4, 19, 20]; however, their efficacy in addressing infertility remains constrained [21]. Consequently, assisted reproductive technology (ART) is progressively regarded as the principal strategy for achieving fertility in these patients [22].

Although initially presumed to be a standard case of Zinner syndrome, the findings indicate an atypical developmental variant. The observed history of decreasing semen volume and the fusion of the right seminal vesicle with the cyst suggest the potential for acquired inflammatory changes. In patients with complete obstructive azoospermia, diagnostic vasography (DVG) continues to be instrumental in precisely identifying obstructions and informing treatment strategies, especially in scenarios where surgical intervention may not rectify infertility.

The patient articulated that prior to surgery, his primary objective was the excision of the cyst to address his infertility concerns. He did not anticipate receiving a diagnosis of atypical Zinner syndrome but has since reconciled with it. During subsequent follow-up, he noted the resolution of his preoperative symptoms, which included the sensation of incomplete defecation and mild anal distension, following the surgical intervention. Despite this symptomatic improvement, he acknowledged the potential persistence of infertility and proactively engaged in assisted reproductive techniques. These efforts proved successful, culminating in a pregnancy with his partner, which brought them significant relief and joy.