Magnetic resonance imaging in the diagnosis of seminal vesicle cysts and associated anomalies.

Seminal vesicle cysts are rare. Usually these lesions are asymptomatic and treatment is unnecessary. Definitive diagnosis can prove difficult, which has resulted in the use of invasive, potentially hazardous ultrasound guided aspiration and instillation of contrast medium with the associated risk of infection and abscess formation. We report 2 cases where magnetic resonance imaging (MRI) provided a conclusive diagnosis without the need for invasive diagnostic tests. CASE REPORTS Case 1. A 22-year-old male presented complaining of dysuria and suprapubic discomfort 2 weeks in duration. Ultrasound and excretory urography were performed, and the probable diagnosis of right ureterocele was made. Multiplanar T1 and T2weighted MRI revealed a 4.1 cm abnormality on the right side situated between the bladder and seminal vesicle, and a convoluted tube extending from its posterior aspect to the right seminal vesicle (figs. 1 and 2). The abnormality demonstrated high signal intensity on T1-weighted sequences, suggesting the presence of proteinaceous fluid and not urine or simple fluid within the lesion. The features were those of a seminal vesicle cyst in association with an absent ipsilateral kidney. Case 2. A 15-year-old male presented with mild discomfort on voiding. MRI was diagnostic, showing a seminal vesicle cyst on the left side with associated ipsilateral renal agenesis. Examination with the patient under anesthesia revealed a palpable fluctuant mass superior to the prostate on the affected side, and cystoscopy confirmed the absence of a ureteral orifice. DISCUSSION The reproductive and renal systems are embryologically derived from the mesonephric duct. Anomalies of the seminal vesicles are commonly associated with abnormalities of other structures derived from the mesonephric duct, for example the vas deferens, kidney and ureter. One well recognized association is seminal vesicle cyst and ipsilateral renal agenesis. 1 Mostly these cysts are asymptomatic and treatment is unnecessary. When symptoms occur they are varied and include perineal pain, scrotal pain, pain on defecation, dysuria, urinary frequency and urgency, and pain on ejaculation. Bladder outlet obstruction and ureteral obstruction have been observed, as have recurrent urinary tract infection, epididymitis and chronic prostatitis. 2 Pelvic and transrectal ultrasound, excretory urography and computerized tomography have thus far formed the mainstay in the diagnosis of seminal vesicle cysts. Often there is difficulty in distinguishing these cysts from entities such as ureteroceles. 3 Moreover, ultrasound guided aspiration and instillation of contrast medium, which are commonly used, are associated with a risk of infection and abscess formation. In these 2 cases use of MRI was paramount in making the diagnosis of seminal vesicle cyst without the need to resort to more invasive investigations. The detection of a convoluted tail connecting the cystic abnormality to the seminal vesicle was pivotal in making the diagnoses. In addition, the presence of fluid of high signal intensity on T1-weighted sequences was helpful, as other lesions such as ureteroceles and simple cysts would be of low signal intensity on T1-weighted images.