Müllerian duct cyst

A Müllerian duct cyst is a cyst that arises from remnants of the Müllerian duct and is one of the midline cystic masses in the male pelvis. 

Epidemiology

Müllerian duct cysts usually occur in the 3^rd and 4^th decades of life (whereas prostatic utricle cysts are most often detected in the 1^st and 2^nd decades).

Clinical presentation

Müllerian duct cysts may be incidental. If large enough, can cause obstructive or irritative urinary symptoms, e.g. hematuria, ejaculatory impairment, or suprapubic/rectal pain ².

Complications

• may contain pus or hemorrhage if infected

Pathology

During male fetal development, the paramesonephric (Müllerian) ducts mostly regress, save for the uppermost and lowermost segments, which contribute to the developing testes (eventually the appendix testes) and prostatic utricle, respectively ⁵. 

Müllerian duct cysts represent focal incomplete duct regression, and thus can arise anywhere along this path of Müllerian duct regression, from scrotum to prostatic utricle. This is in contrast to prostatic utricle cysts, which always arise at the level of the verumontanum and are always in the midline. The embryologic origin also explains why Müllerian duct cysts are larger and often extend superior to the prostate gland, while utricle cysts are usually smaller and are less likely to extend above the prostate gland.

Müllerian duct cysts do not communicate with the urethra.

Müllerian duct cysts are not associated with other abnormalities (utricle cysts are associated with a variety of genitourinary abnormalities).

Radiographic features

Müllerian duct cysts are seen on pelvic MRI or ultrasound as midline cystic lesions in the prostate that do not communicate with the urethra. The cysts may contain pus or hemorrhage if infected.

Treatment and prognosis

In many cases no treatment is required at all. However if symptomatic then intervention may be required. Options available include ⁷:

• transrectal ultrasound-guided aspiration and injection of sclerosing agents
• surgery
  • transurethral cyst incision drainage
  • open cyst resection
  • laparoscopic cystectomy

Complications

• may contain cancer (i.e. endometrial carcinoma, clear cell carcinoma, or squamous cell carcinoma) with a reported prevalence as high as 3% ²

History and etymology

The Mullerian ducts were named after Johannes Peter Müller (1801-1858), a pioneering German physiologist and comparative anatomist who described his eponymous ducts in his text "Bildungsgeschichte der Genitalien" in 1830 ⁶.

Differential diagnosis

• prostatic utricle cyst - can be very difficult or impossible to distinguish from a Müllerian duct cyst ²
  • communicates with urethra
  • may contain spermatozoa on aspiration
• prostatic abscess ²

See also

• cystic lesions of the prostate