Zinner syndrome

Case contributed by Dr Adan Radiology Department

Presentation

Non-specific symptoms, such as left loin pain and intermittent scrotal pain.

Patient Data

Age: 30 years
Gender: Male

Non-enhanced CT KUB

CT
  • ovoid-shaped homogeneous fluid lesion hyperdense to urine at the left retrovesical region, measuring about 7.5 x 6.0 x 5.5 cm, significantly indenting the urinary bladder
  • prominent right seminal vesicle
  • the left kidney is absent
  • the right kidney is hypertrophied, in normal location and orientation. No renal calculi, hydronephrosis, contour deforming abnormality or perinephric collection
  • the right ureter and the urinary bladder are unremarkable
  • the visualized parts of the liver, gallbladder, common bile duct, pancreas, spleen, adrenals, and bowel loops show no gross abnormality, although this is a suboptimal study due to lack of contrast media
  • no free intra-abdominal fluid or air or significant lymphadenopathy detected
  • both lung bases are clear
  • the visualized parts of the bones show no evidence of destructive lesions

Impression:
A left seminal vesicle cyst is a high probability, with absence of the left kidney. For further investigation by MRI pelvis.

Pelvic MRI.

MRI
  • large, sharply demarcated cystic mass, displaying high signal intensity on both T1 and T2 (reflecting increased concentration of proteinaceous material or hemorrhage), markedly indenting/compressing the posteroinferior aspect of the urinary bladder. It shows no diffusion restriction on DWI or contrast enhancement on the post-contrast scan. From its posterolateral aspect emerge two tubular structures; one is identified as obstructed left ejaculatory duct and the other - an ectopic ureter
  • the right seminal vesicle does not show any abnormality
  • the urinary bladder is well-distended but compressed at its posteroinferior aspect, as aforementioned. It shows average wall thickness. No focal area of altered signal intensity in the wall or lumen of the urinary bladder. The perivesical fat shows average signal intensity
  • the prostate is normal in size and shows a smooth outline and normal zonal anatomy and signal intensity. The periprostatic fat shows normal signal intensity
  • the visualized bowel, including the rectum, shows normal MR morphology and signal intensity
  • no significant pelvic lymphadenopathy
  • no free fluid

Impression:
Known left-sided renal agenesis with abovementioned ipsilateral seminal vesicle cyst and dilatation of the ejaculatory duct comprise the Zinner syndrome triad.

Annotated images

CT

Axial images of the CT scan show a single right kidney (green arrow) with an empty left renal fossa ( orange arrow ) a homogeneous liquid mass left-sided retrovesical seminal vesicle cyst (red arrow), compressing the urinary bladder and protruding into it.

Case Discussion

A 30-year-old male patient with no past medical or surgical history presented with non-specific left groin pain. He had an abdominal ultrasound (not available) that showed a single right kidney and left-sided pelvic cystic mass with turbid content. CT was requested.

CT shows left renal agenesis and seminal vesicle cyst but may be insufficient to confirm the diagnosis, for which MRI was recommended.

A pelvic MRI was performed to accurately identify the origin of the cystic mass. MRI is confirmatory and makes the definitive diagnosis of a seminal vesicle cyst, which appears in both T1WI and T2WI as a hyperintense structure (due to hemorrhage and a high proteinaceous concentration in the seminal fluid). 

The patient in our case complained of nonspecific symptoms - the most common presentation. Patients with Zinner syndrome show a triad comprising unilateral renal agenesis, ipsilateral seminal vesicle cyst, and ejaculatory duct obstruction

A differential diagnosis such as prostatic utricle cysts or acquired seminal vesical cysts could be ruled out based on imaging findings and patient history. 

 Characteristic radiological appearance of Zinner syndrome is sufficient for the radiologist to arrive at an accurate diagnosis.

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