Congenital cysts of the prostate or periprostatic tissues include utricular, mullerian duct, ejaculatory duct, ampulla of vas deferens, seminal vesicle, and prostatic cysts. The location of the cyst and presence or absence of communication with the urethra are important diagnostic features in order to distinguish amongst these cysts.
Utricular and mullerian duct cysts are midline. Utricular cysts are the most common type of congenital cyst.
The prostatic utricle is a short, blind-ending pouch located on the verumontanum (ie, the floor of the prostatic urethra) that represents a mesodermal remnant of the Müllerian tubercle formed by the fused, paired distal müllerian ducts. In males, the müllerian ducts regress under the influence of müllerian inhibiting factor produced by the fetal testis, leaving the prostatic utricle as a vestige. Because regression of the utricle is androgen mediated, utricular cysts are found with increased frequency in boys with other disorders, such as hypospadias, prune-belly syndrome, cryptorchidism, and pseudohermaphroditism. An opacified prostatic utricle is usually well demonstrated at lateral VCUG, appearing as a posterior urethral diverticulum. They do not extend above the base (superior portion) of the prostate gland. Occasionally, urethral diverticula may be gigantic.
Mullerian duct cysts form from remnants of the mullerian duct that normally regress in utero. They are connected to the veromontanum by a stalk but do not communicate with the urethra, and usually extend above the base of the prostate in a retrovesical location. They are usually asymptomatic but may present in childhood with symptoms of urinary tract infection or urinary retention. They are uncommonly associated with renal agenesis.
Ejaculatory duct and ampulla of vas deferens cysts generally lie posterior to the urethra, laterally but close to the midline. If large they may be difficult to distinguish from utricular and mullerian duct cysts.
Seminal vesicle and prostatic cysts are usually lateral, protrude into the bladder, and present in the third decade of life. They are often associated with ipsilateral renal agenesis.