Zinner’s syndrome is a rare congenital malformation of the seminal vesicles and ipsilateral upper urinary tract (1). It is considered to be the male equivalent of Mayer-Rokitansky-Kuster-Hauser syndrome, which is seen in females (3). The relationship between upper urinary tract abnormalities and seminal vesicle malformations results from the common origin of the ureteric bud and the seminal vesicles, which stem from the mesonephric (Wolffian) duct (4). An incident occurring during the first trimester, especially prior to the seventh week of gestation, can cause the maldevelopment of the distal part of the Wolffian duct, thereby resulting in atresia in both the ejaculatory duct and the ureteric bud (5). If the ureteric bud develops in a more cephalic position in relation to the mesonephric duct blastema, it will cause the delayed absorption of the caudal mesonephric duct as well as an emptying problem in the mesonephric duct derivatives, for example, the ejaculatory duct or the seminal vesicles (1,6). Thus, secretions will accumulate in the seminal cyst due to these drainage problems. Generally speaking, renal agenesis is unilateral and ipsilateral. Only three cases involving agenesis on the contralateral side are found in the literature (7).
Most patients with this anomaly remain asymptomatic until the second or third decade of life, which corresponds to the period characterized by the highest level of reproductive activity. Prior to this period, such malformations tend to be detected only incidentally during imaging procedures performed for other reasons. Symptoms occur after the progressive expansion of the seminal vesicles due to the accumulation of secretions that results from the insufficient drainage that is secondary to the ejaculatory duct obstruction (4). Cysts larger than 6 cm may cause pressure on the bladder or prostate, and they may also cause obstructive symptoms.