Zinner syndrome: a radiological journey through a little known condition.

Zinner syndrome is a rare congenital urological entity, secondary to an alteration in embryogenesis between 4th and 13th weeks of gestation, specifically because of abnormalities in the development of the distal mesonephric duct. It is characterized by the triad of unilateral renal agenesis, cystic dilatation of the ipsilateral seminal vesicle and ipsilateral ejaculatory duct obstruction. The aim of this article is to provide the reader with all the necessary information to be able to suspect the presence of this syndrome, reviewing its physiopathology, clinical manifestations and the imaging techniques that enable its diagnosis, emphasizing those radiological findings by MRI that should lead us to think about it. This work is illustrated with representative radiological images of cases belonging to our institution, including patients with different variants of Zinner syndrome. We also include an overview of the embryology of the male urogenital system, to remember the role of the mesonephric duct and the ureteral bud in the formation of the different urogenital structures, as well as a differential diagnosis that allows us to differentiate seminal vesicle cysts from other pelvic cystic lesions.