Prostatic and Paraprostatic Cysts

Introduction

Prostatic and paraprostatic (periprostatic) cysts are fluid-filled pockets associated with the prostate.

These occur uncommonly in male dogs of medium or large breeds.

Prostatic cysts usually result from an obstruction of prostatic ducts and fluid retention within the prostatic parenchyma. There are usually multiple cavitary areas within the gland which potentially connect with the urethra.

Paraprostatic cysts are thought to originate from the blind-ended uterus masculinus, formed from the müllerian duct system. These are usually very large structures which extend into the abdominal cavity or the pelvic canal. These cysts attach to the prostate but do not communicate with the urethra. The fluid contained within the cysts is usually pale yellow to orange. The interior of the cysts is smooth and cartilage or calcified areas may be present.

Cysts usually cause signs associated with compression of intestinal or urinary structures. There may also be an inflammatory component with adhesions, manifested by abdominal pain and haematological changes.

If prostatic cysts become infected they may then become prostatic abscesses. Paraprostatic cysts are less likely to become secondarily infected as they have no communication with the urogenital tract.

Clinical Signs

Clinical signs may be absent until the cyst is very large.

Pressure on the urethra and displacement of the rectum and colon can lead to signs such as: dysuria, haematuria, constipation and tenesmus.

Pelvic pain can lead to an abnormal gait. Abdominal enlargement is sometimes obvious.

Diagnosis

Rectal examination may enable palpation of cysts in the pelvic canal.

Abdominal radiographs may show: a caudal abdominal mass, directed in a cranial-caudal direction, which may be calcified. A retrograde contast urethrogram may help differentiate the cyst from the bladder.

Ultrasonography will also enable to differentiate the cyst from the bladder, and will show a thin-walled structure with relatively anechoic fluid. Aspirated fluid is usually yellow but may contain blood. Bacterial culture is negative unless there is secondary infection.

Treatment

Medical treatment is not effective. Small cysts can sometimes be managed by draining the cyst several times and castrating the animal.

In most cases, castration is recommended in conjunction with surgical resection of the cyst. If complete excision is not possible, the remaining portion should be omentalised by suturing a leaf of omentum in place.

Omentalisation is the most effective way to deal with prostatic and paraprostatic cysts, as it provides a source of blood supply to deliver antibiotics, white blood cells and angiogenic factors, and acts as a physiological drain.

Marsupialisation is another treatment option, and the cyst wall is sutured to the skin to form a semi-permanent stoma. Management of a marsupialised stoma can sometimes be difficult.

Prostatic and Paraprostatic Cysts Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Soft Tissue Surgery Q&A 03

References

Tobias, K. (2009) Manual of small animal soft tissue surgery John Wiley and Sons

Green, R. (1996) Small animal ultrasound Wiley-Blackwell

Slatter, D. (2002) Textbook of small animal surgery Elsevier Health Sciences