A 61 year-old male with a history of metabolic syndrome (hypertension, obesity, dyslipidemia), left kidney agenesia, compensatory hypertrophy and previous stone disease of the contralateral kidney, was sent by his general practitioner to our department because the incidental diagnosis of left seminal vesicle cyst lesion, not documented in the previous annual ultrasound control. He was father of 2 children and did not complain any lower urinary tract symptoms (LUTS) with a satisfied sexual life. He had a previous history negative for urinary tract infections (UTIs), dysuria, hematuria, ejaculatory pain, prostatitis, epididymitis. The examination revealed a patient in good general condition with body mass index of 29.07. The abdomen was soft with no palpable mass. Digital rectal examination was a normal prostate according with age. Laboratory tests including urine culture and PSA showed no abnormality. Transabdominal ultrasound scan (US) confirmed left kidney agenesia with compensatory hypertrophy and revealed for the first time (not doc- Copyrights 97 Case ReportOpen AccessUrology Clinic, Department of Surgery, Dentistry, Paediatrics and Gynaecology, University of Verona, Italy AbstractSeminal vesicle cysts combined with genitourinary anomalies, named since 1914 Zinner's syndrome, are rare. We present a case of asymptomatic 61-year-old married man, with known left kidney agenesia and a previous ultrasound history negative for vesicle cyst since one year before. Digital rectal examination was normal. Diagnostic imaging (both ultrasound and magnetic resonance imaging) showed left seminal vesicle cyst without any intravesical protrusion. In the absence of symptoms, a conservative treatment was decided, with a strict clinical and ultrasonographic follow-up. The diagnosis of Zinner's syndrome was made later, by ultrasound and magnetic resonance imaging, with the development of multilocular seminal vesicle cystic lesion, with a rapid onset (within one year). This malformation should be considered in the differential diagnosis of a pelvic cyst in male patients with renal agenesis. So far, the patient was asymptomatic and had never presented with dysuria, signs of bladder obstruction or urinary tract infection. He had neither any perineal discomfort nor pain; he described normal ejaculation without pain, no hematospermia, and had never experimented any urinary infection or prostatitis. He also had a normal sexual activity. In this particular case, in the absence of symptoms a conservative treatment was decided, with a strict clinical and transrectal US follow-up, at least until