Prostatic Cysts

1. Midline cyst

 (a) Prostatic utricle cyst (PUC)

 (b) Cystic utricle (or cystic dilation of the prostatic utricle)

 (c) Enlarged prostatic utricle

2. Cysts of the ejaculatory ducts

3. Parenchyma cyst

 (a) Simple parenchymal cysts

 (b) Multiple parenchymal cysts (ductal ectasia or microcysts)

 (c) Small cystic parenchymal nodules

 (d) Large cystic parenchymal nodules

4. Cyst complicated

 (a) Cysts complicated by infection

 (b) Hemorrhagic cysts

5. Cystic tumors

 (a) Cystadenoma

 (b) Cystadenocarcinoma or high-grade tumor

 (c) Dermoid cyst

6. Parasitic cysts

Table 22.2
Prostatic cysts classification with subclassification, essential characteristics and treatment


Anatomical location/US features



Differential diagnosis


1. Midline

 (a) Utricular

 (b) Cystic dilatation

 (c) Enlarged prostatic utricle

Round shape and anechoic

Absent communication with urethra

Presence of communication with urethra

Wide opening in the prostatic urethra

Clear liquid without sperm

Congenital or acquired

Bladder diverticula

Ejaculatory duct cyst


Simple cyst

Transperineal aspiration and alcohol injection in noncommunicating cyst, TURED if symptoms or communicating cyst

2. Cysts of the ejaculatory ducts

Paramedian or lateral, above the verumontanum, could touch the seminal vesicle


Congenital or acquired


Midline cyst

Duct dilatation

Aspiration, resection, retrograde endoscopic dilatation if infertility, or hemospermia

3. Parenchyma

 (a) Simple

 (b) Multiple/microcysts

 (c) Small cystic nodules

 (d) Large cystic nodules

(a) Single or multiple, sizing 0.5–9 cm, subcapsular or paraurethral

(b) Oval, small anechoic space of 1 mm

(c) and (d) Cysts <1 cm grape shape, with pseudocapsule containing several cysts (1–20 mm)

Clear liquid without sperm

Congenital or acquired

BPH retention of prostatic fluid, inflammation, atrophy, and cystic degeneration of BPH

Midline cyst

Ejaculatory duct cyst




BPH medical therapy

TURP (or deroofing)

if urinary symptoms

4. Complicated cyst

 (a) Infection

 (b) Hemorrhagic

Irregular iso-/hyperechoic liquid collection

(a) Not well-defined border

(b) Well-defined borders

Purulent or hemorrhagic secretions

Abscess (es.TBC)

Hemorrhagic infarction and hematoma after biopsy

Parasitic cyst

Pararectal abscess


If symptoms not responsive to antibiotics:

Percutaneous drain placement TURP

5. Cystic tumors

 (a) Cystadenoma

 (b) Cystadenocarcinoma

 (c) Dermoid cyst

(a) Large and complex cyst with iso-/hypoechoic content, invading (the bladder, rectum, and seminal vesicles) without infiltration, pseudocapsule is present

(b) Absence of pseudocapsule, infiltrating pelvic organs

(c) Hyperechoic content (squamous diff.)

Biopsy or TURP

Cytology is not useful

Cancer transformation of the cuboidal epithelium of the cyst

Grandi noduli cistici

Ductal cancer with cystic pattern

Others neoplasms (colon, metastasis)

Computerized tomography or magnetic resonance

(a) Prostatectomy

(b) Cystoprostatectomy ±

radiation/hormonal therapy

(c) Observation or surgery

6. Parasitic cyst

Single or multiple large cysts with compressing pattern of growth without infiltrating

Parasitic tests


Bilharziasis, Hydatidosis infection

Large cystic nodules

Ductal cancer

Medical treatment

Transperineal drain with cytology analysis

TURED transurethral resection of the ejaculatory ducts, BPH benign prostatic hyperplasia, TURP transurethral prostatic resection

22.2 Classification of Cystic Prostatic Lesions

22.2.1 Midline Cysts

Three distinct categories come under this heading: (a) prostatic utricle cyst (PUC), (b) cystic utricle (or cystic dilation of the prostatic utricle), and (c) enlarged prostatic utricle. This is in agreement with Kato et al. [8, 9], who proposed a subclassification of these cysts according to whether they have an outlet to the urethra: a utricular cyst has no outlet, while a cystic utricle has an obliterated and an enlarged prostatic utricle an open urethral outlet. US identification of an outlet from the cyst to the urethra is not always possible or easy to document, especially in cases with an obstructed outlet, where it will appear as a hyperechogenic stripe surrounded by a narrow hypoechogenic rim. Histologically, it is always possible to demonstrate the outlet [8, 9].

Another classification in the literature was published by Ritchey et al. [10], in whose subdivision, utricular cysts were denominated Ritchey Type 1. However, this classification has the limit that it defines cysts according to the site, whereas not all midline cysts are utricular cysts. In fact, a differential diagnosis must be made among midline cysts, parenchymal cysts, and cystadenomas. Utricular Cysts

These are denominated cysts of the Müllerian ducts by some authors. At US, they appear as rounded or oval formations that can also be palpable and as large as several centimeters in diameter. They are localized on the midline, proximally to the seminal colliculus, and extend inside the prostatic base toward the insertion of the seminal vesicles (Fig. 22.1). Histologically, there is no communication with the urethra, and the utricle has a normal morphology with a cuboid or columnar epithelium [8, 9]. Infectious complications of these cysts are less frequent because of the lack of communication with the urethra. Yasumoto et al. reported the characteristics of the fluid aspirate obtained by transperineal puncture of midline cysts, referring that the fluid did not contain spermatozoa and the prostate-specific antigen (PSA) concentration in the fluid was 90,000 ng/ml [11].


Fig. 22.1
Midline cyst (a, b). Macrosection of a radical prostatectomy surgical sample with a voluminous utricular cyst (c). US appearance of the prostatic utricular cyst (bn bladder neck, sv seminal vesicle) (d) Cystic Utricle

Unlike utricular cysts, in a cystic utricle, there is an outlet from the cyst to the urethra, which is why it can also be called a cystic dilation of the utricle. It is drop shaped (owing to the communication with the urethra) or ovoid and localized on the midline. It is sometimes indistinguishable from a utricular cyst as regards the site and US features, although in other cases, it is possible to identify a virtual (obliterated) or a real (pervious) outlet. The former picture is visible as a hyperechogenic line at the level of the seminal colliculus surrounded by a narrow hypoechogenic rim (Fig. 22.2). On the basis of embryological studies, it seems that these cysts develop during the last stages of maturation of the utricle as a consequence of an obstruction of the physiological communication with the urethra. Histologically, the communication between the urethra and the cystic utricle is recognizable [8]. Infectious complications of these cysts are frequent because of the urethral outlet, and so they may have a homogeneous content (see infected cyst).


Fig. 22.2
Midline cyst Journal of Urology. Cystic utricle: (a, b) cyst wall showing microcalcifications (c, d) complicated cyst with a dyshomogeneous content due to infection. The cystic utricle outlet to the urethra (that is functionally obstructed) appears as a narrow hypoechoic line (at longitudinal scanning) connecting it to the seminal colliculus Enlarged Prostatic Utricle

This shows a characteristic, wide outlet from the utricle to the urethra. It is a congenital malformation that is also known as a remnant of the Müllerian duct or a male vagina and is generally diagnosed in youths or boys with other malformations like hypospadias or virilization defects. It is not a true cystic formation, because a wide defect is present that causes an ample passage between the utricular cavity and the urethra. The seminal colliculus is sometimes absent, while a dilated tubular structure with a squamous epithelium is evident at histology [9]. Both at US and at retrograde cystourethrography, a cyst with an anechoic content is evident on the posterior midline, showing an ample outlet to the prostatic urethra (Fig. 22.3). The enlarged utricle corresponds to a Ritchey Type 2 cyst [10]. Symptoms include urinary infections, recurrent epididymitis, pain, and post-micturition dribbling. The cyst cavity may be palpable during rectal exploration. Rarely, complications such as calculi in the cystic cavity or neoplastic degeneration can be observed (reported by Sondergaard et al. in 6.3 % of autopsies) [12]). The tumors that can originate from these structures have a distinct histology, prognosis, and clinical behavior: those that originate from the multistratified epithelium of the cyst wall give rise to squamous carcinoma, whereas those that originate from the ductal epithelium of the seminal colliculus develop into ductal (or endometrioid) adenocarcinoma [13].


Fig. 22.3
Acquired cystic enlargement of the ejaculatory ducts (c, arrow) due to the presence of calculi at the level of the outlet to the prostatic urethra. Calculi appear as hyperechoic with black shadow (arrow) (a, b)

22.2.2 Cysts of the Ejaculatory Ducts

Cysts of the ejaculatory ducts are rare and may be congenital or acquired. Cyst can be unilateral or bilateral, rounded or oval, localized in the paramedian site lying between the verumontanum and the bladder neck, and extended from the paraurethral site to the base of the prostate (Fig. 22.4). Cysts of the ejaculatory ducts are linked to obstruction or compression and can contain spermatozoa, but some of these cysts have no outlet. Microscopic examination of the fluid is essential to identify spermatozoa, aspirated transperineally to reduce the risk of infection. In addition, puncture of these cysts combined with chromatography using iodinated contrast medium makes it possible to check for any outlet to the urethra or seminal tracts.


Fig. 22.4
Simple parenchyma cysts located close to the bladder neck and prostatic urethra that cause obstructive urinary symptoms. Ultrasound axial viewof simple (a) and loculated (c) cyst; longitudinal view (b) of simple and loculated (d) cyst

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Jul 10, 2017 | Posted by in UROLOGY | Comments Off on Prostatic Cysts
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