Ch 113 prostate Flashcards
anatomy
- bilobed structure that completely encircles the proximal urethra immediately caudal to the bladder
- endodermal origin and arises from the pelvic urethral epithelium
- composite collection of mesenchymal, urethral, and Wolffian duct tissue with glandular and nonglandular components bound within a common capsule.
- remains abdominal until the urachal vestige breaks down at 2 months of age, at which time it occupies a pelvic position
- At puberty the gland enlarges and migrates to occupy a partially abdominal position.
- adult life the gland continues to undergo hyperplastic enlargement and migrates further cranially
- prostatic arteries branch from the internal pudendal vessels
- significant anastomoses between the prostatic arteries and the urethral and cranial and caudal rectal arteries
- autonomic nerve supply to the gland is via the hypogastric and pelvic nerves
What is the normal size of the prostate?
What breed can have a healthy larger prostate?
0.64-0.96g/kg
Scottish Terriers
Is the prostate peritoneal or retroperitoneal?
Both! Its ventral aspect is retroperitoneal
What nervous input increases glandular secretion?
Parasympathetic suppy from the pelvic nerve
histology
- comprises secretory epithelial tissue contained within a stromal capsule of fibrous, elastic, and smooth muscle tissue.
- The epithelial tissue is subdivided into distinct lobules by smooth muscle septa
- characterized by compound tubuloalveolar glands,
What are the 2 forms of acinar gland dilation seen within the mature prostate?
- Simple dilatation: Many dilated acini with or without luminal oesionphilic secretions which no not compress adjacent acini
- Focal glandular ectasia: Focal dilatation of a few acini with oesinophilic content and compression of the adjacent prostatic parenchyma
List the functions of the prostatic secretions
- Promote spermatozoa motility and viability
- Increase uterine perfusion
- Modulate neutrophil-induced inhibition of spermatazoa attachment to uterine epithelium
What substances are found within prostatic secretion
- High concentration of zinc and zinc-binding proteins
- Acid phosphatase (also produced by epididymis)
- Canine prostate-specific esterase (90% total protein)
- Large amounts of PGE2
hormonal regulation
- continues to undergo progressive androgen-mediated enlargement throughout life as the consequence of benign prostatic hyperplastic changes
- 50% by 5 years and 70% by 8 to 9 years
- Two distinct forms of BPH glandular and complex, are recognized (glandular in younger dogs (<4 to 5 years), complex hyperplasia is the more common form after that age
- glandular form: confined to the secretory cells, which increase in number and size, giving rise to a symmetric enlargement. testosterone regulates gene expression in the nuclei to control prostatic growth
- increased responsiveness to androgens by the prostate as it ages
- changes of complex prostatic hyperplasia involve primarily the stromal elements69 and are characterized by an asymmetric enlargement
- Estrogens are thought to play a role in the pathogenesis of benign prostatic hyperplasia,
Diagnostics
- Dogs with prostatic enlargement may have concurrent perineal hernias; thus pelvic diaphragm status should be evaluated
- transurethral washing, or aspiration of fine needle samples.
- gland is normally surrounded by periprostatic adipose tissue and hence appears to have a radiolucent margin that allows it to be distinguished
ultrasound
- BPH: increase in the overall gland size, a heterogenous increase in echodensity, and small focal areas of echolucency. Cystic changes are also common
- Abscessation appears as a progression of this, with highly characteristic hyperechoic capsular and loculated tissue
- Discrete prostatic cysts have a hyperechoic fluid ultrasound appearance
What is glandular BPH?
- predominates in younger dogs
- Secretory cells increase in number and size leadng to symmetric enlargement
- Testosterone is metabolised by 5alpha-reductase in the prostate to 5alpha-dihydrotestosterone
- Regulates gene expression in the nuclei to control prostatic growth
What is complex BPH?
Most common form, predominates in older dogs
As the prostate increases in size, 5alpha-dihydrotestosterone concentrations decrease
Paralleled by increase in metabolism of androgens within the prostate and increasing numbers of nuclear androgen receptors (increases responsiveness to androgens and decrease in apoptosis)
Asymmetric enlargement, envolving both glandular and prominent stromal elements
How is oestrogen throught to play a role in BPH?
- Increases the sensitivity of the prostate to dihydrotestosterone bu inducing nuclear dihydrotestosterone receptors and promoting stromal and collagen synthesis
- May also exert inhibitory role on cell death
What are the Tx options for BPH?
- Castration - resolution within a few days
Medical:
- Antiandrogens - delmainone acetate. Progestogen with antiandrogenic and antioestrogenic activity by suppressing interstitial cell function. Flutamide binds to dihydrotestosterone receptors
- LH Inhibitors - Megestrol acetate, medroxyprogesteronei - progesterone derivatives that inhibit LH release and suppress 5alpha-reductase. May induce squamous metaplasia
- GnRH agonists/analogues - block pituitary receptor sites, causing reduction in natural LH-RH and decline in testicular secretion of testosterone. Can be given as long acting injection or implant
- 5alpha-reductase inhibitor - Finasteride
- Oestrogens - Can cause BM aplasia and prostatic metaplasia…
dyschezia is the most common clinical sign
prostatitis
- The most common route of infection is considered to be ascending via the urethra
- suggests that benign prostatic hyperplasia is an important prerequisite
- dyschezia and pain on defecation; pain on urination is also commonly seen. A purulent or sanguineous penile discharge (+/- pyrexia)
- Prostatic abscesses have a highly characteristic and virtually pathognomic multiloculated appearance on ultrasound
- FNA sampling
List the natural defense mechanism against bacterial prostatitis
- SHedding or uropathogens bound to exfoliating urethral cells
- bacterial trapping by secreted mucous
- Intermittent washout by urine
- Local immunoglobulins, cytokines and defensins
- Mobilisation of leucocytes
What is the most common bacterial cause of prostatitis?
E.Coli
List the surgical options for prostatic abscessation
- Castration and ABx
- marsupialisation (rarely done)
- Active or passive drainage (20% mortailty)
- Omentalisation (consistently sucessful, low complications)
- Partial prostatectomy (risk of incontinence and severe haemorrhage)
What ABx have good penetration of the blood-lipid barrier of the prostate?
- Enrofloxacin
- Marbofloxacin
- TMS
- Chloramphenicol
Barrier is likely less functional in the inflamed prostate so this is of unclear significance
Discrete Prostatic Cysts
- large solitary cysts is less common. Their cause still remains unclear,
- “paraprostatic” cysts, which appear to develop separately from the prostate and do not communicate with the parenchyma but usually have some attachment to the capsule
- “prostatic” cysts, which develop within the capsule of the gland itself
- speculation that paraprostatic cysts represent an anomaly of embryonic remnants of the Müllerian ducts has never been substantiated in dogs.
What are the surgical options for prostatic cysts?
Complete resection if small and minimally attached
Partial resection and omentalisation
What is the most common form of prostatic neoplasia?
Adenocarcinoma
Androgen receptor negative - castration is not an effective Tx
increased incidence and more frequent development of pulmonary metastasis in castrated dogs
(prepubertal castration may be protective)
ddx SCC, transitional cell carcinoma, and undifferentiated carcinoma
What gene has been associated with an increased risk of prostatic carcinoma?
short CAG-1 repeats in the andorgen receptor gene
How can prostatic carcinomas be subclassified?
Differentiation
- glandular
- urothelial
- squamoid
- sarcomatoid
Growth patterns:
- papillary
- cribiform
- solid
- small acinar/ductal
- signet ring
- mucinous
Consistent aggressive with high met rate 80% and 20% mets to axial skeleton
What % of prostatic carcinoma cells express COX-2?
75%
What are the Tx options for a prostatic carcinoma?
- Tube cystotomy or urethral stenting for palliation
- NSAIDs - improve survival
- complete prostatectomy (significant postoperative complication rate (particularly incontinence) with progression of dz)
- Radiation (Stereotactic irradiation to a precisely focused target, Intensity-modulated radiation allows dose to conform more precisely to the three-dimensional shape of the tumor)
- Nd:YAG partial prostatectomy
prognosis for canine prostatic carcinoma is guarded because of the aggressive nature
List anatomical differences of the feline prostate
Only partially encircles the urethra (dorsolaterally)
Can have some prostatic tissue disseminated within the urethral wall caudal to the prostate
Sx
- involve some potential for intraoperative contamination; patients should therefore receive broad-spectrum perioperative antibiotic therapy
- placement of the urethral catheter aids identification of the prostatic urethra
- prostatic vascular supply and hypogastric and pelvic nerves are found on the dorsal aspect of the prostate,
Prostatic Abscesses/cyst sx
- Stab incisions
- oculations within the parenchyma are then broken down by digital exploration
- flush and suction
- cyst: To avoid risky area dissections, the cyst is partially resected, leaving the attachment of its base to the prostate gland intact.
Ventral Drainage
- Drains are left in situ until the bulk of the fluid drainage subsides
- complications, development of urethrocutaneous fistulas, premature drain loss, and mortality rates of 20%
Omentalization
- The physiologic drainage properties of the omentum
- omentum is packed into the cavity and anchored with mattress sutures through the capsular wall.
- eported to be consistently successful for the management of prostatic abscesses; compared with other drainage techniques,
- postoperative complication rates are low
- Recurrence
- Omental metastasis or seeding
partial prostatectomy
- consdier emporary occlusion of prostatic vascular supply
- use of a vessel sealing device
- ultrasonic aspirator, which emulsifies and aspirates the tissue
- urethra is pressure tested for any signs of leakage
- complications: incontinence, hameorrhagem recurrence
Total Prostatectomy for Neoplasia
- carcinoma: condition’s generally poor prognosis and the procedure’s lack of impact on the systemic disease
- pubic symphysiotomy to improve access to the pelvic urethra.
- onsiderable potential for hemorrhage, and temporary aortic occlusion
- urethra is catheterized
- Length of urethra to be sacrificed> An end-to-end anastomosis
- catheter remains in situ for 5 to 7 days postoperatively
- Urinary incontinence is likely after total prostatectomy
Investigation of the use of microwave ablation with and without cooling urethral perfusion for thermal ablation of the prostate gland in canine cadavers
Traverson 2021
laparotomy with ultrasound-guided MWA-UP
Normograde cystourethroscopy was performed before and after treatment; recorded images were reviewed in a blinded manner for scoring of urethral mucosal discoloration and loss of integrity
urethral mucosal discoloration and loss of integrity were significantly higher (indicating more severe lesions) for the MWA-NP group than for the MWA-UP group.
denuding oof urehtral mucosa present in both groups, otherwise score of 0 for UP on scope.
Overall median percentage prostate gland ablation was 73%;
MWA-UP induced subtotal thermal necrosis of prostate glands in canine cadavers while limiting urethral mucosal injury
Prospective comparison of prostatic
aspirate culture and cystocentesis
urine culture for detection of bacterial
infection in dogs with prostatic
neoplasia
K. A. Skorupski 2022
whether prostatic aspirate culture is a superior
method to detect infection compared to culture of urine
10 dogs
Using prostatic aspirate culture as
the reference standard, urine culture had a sensitivity for detecting infection of 87.5% and specificity of 50%
Study
results did not identify prostatic aspirate culture to be a more sensitive method of detecting prostatic
infection than urine culture collected by cystocentesis
A recent retrospective study of 82 dogs with
prostatitis or prostatic abscessation found that results of urine
and prostatic culture were discordant in 50% of cases and that, in
71% of those discordant cases, the urine culture was negative and
the prostatic culture was positive (Lea et al. 2022).
Surgical treatment and outcome of sterile prostatic cysts
in dogs
Sara Del Magno 2021
Study Design: Retrospective study.
Animals: Forty-four client-owned dogs.
Extra- and intraparenchymal cysts were diagnosed in 29 and 11 dogs, respectively. Four dogs had both types. Extraparenchymal cysts
were treated by partial resection and omentalization (n = 22) and complete
resection (n = 7). Drainage and intracapsular omentalization were performed
in all dogs with intraparenchymal cysts
Resolution was documented in
39/44 dogs (88.6%). Intraoperative complications occurred in one dog (urethral
tear). Major complications resulting in death occurred in three dogs
(oliguric kidney injury, cardiac arrhythmia, and persisting urinary tract
obstruction).
Recurrence occurred in two dogs
Partial or complete resection and/or omentalization of sterile
PCs led to resolution of clinical signs in most dogs, although postoperative urinary
incontinence was frequent (10/44) 22%
Total prostatectomy as a treatment for prostatic carcinoma in 25 dogs
Tristram C. Bennett 2018
Multi-institutional retrospective case series
Urinary anastomotic techniques included urethrourethral anastomosis in 14 dogs, cystourethral
anastomosis in 9 dogs, ureterocolonic anastomosis in 1 dog,
All dogs survived to discharge. Fifteen dogs were diagnosed with transitional cell carcinoma, 8 dogs
with prostatic adenocarcinoma
Permanent postoperative urinary incontinence was present in 8 of 23 dogs (35%). The median survival time was shorter in dogs with extracapsular
tumor extension compared with those with intracapsular tumors.
4 major complications in 4 dogs and 16 minor complications in 15 dogs
Twenty-one dogs received adjunctive therapy, including mitoxantrone and NSAIDs
Local tumor recurrence was confirmed in 3 dogs and suspected in 5 dogs (8/25 - 30%). Metastatic disease was confirmed in 4 dogs and suspected in 9 dogs (13/25 - 50%)
The median DFI was 81.5 days
The overall median survival time was 231 days (189 for TCC)
Death was attributed to tumor-related causes in 19 dogs
Survival times in dogs with prostatic malignancies vary widely, from 17 to 654 days, depending on the stage at diagnosis and treatment pursued
Case selection for this procedure has been
based on criteria, such as small, intracapsular primary lesions, without evidence of metastatic disease
common complication consists of
urinary incontinence, diagnosed in 33%-100% of cases
A total cystoprostectomy was performed
with bilateral ureterocolonic anastomosis in this dog.
Another dog had gross disease involving a large section of the
postprostatic urethra, and an anastomosis between the bladder
neck and penile urethra was performed.
This finding
suggests that the surgical procedure itself cannot account
for urinary incontinence and that, instead, the disease process
contributes to the pathogenesis of this complication
dogs with gross disease extending beyond the prostatic capsule
may not have been deemed appropriate
almost one-third of dogs
survived longer than 1 year after surgery.
Zambelli 2022 – total perineal prostatectomy (concurrent perineal hernia)
- advantages: surgical time reduced, improved visualization/mobilisation of prostate
no need for pelvic osteotomy, subjectively vesicourethral anastomosis easier
- no post-op complications related to prostatectomy, no long-term incontinence
animals
Influence of conventional versus unidirectional barbed suture on leakage pressures in canine vesicourethral anastomosis: An ex-vivo study
Eric Monnet 2023
conventional vs unidirectional barbed suture for canine vesicourethral anastomosis
- no statistically significant difference in acute leakage pressure (8.6mmHg vs 11.7mmHg)
- urethral catheter still required to prevent extravasation
- shorter sx time and fewer suture bites
Comparison of leakage pressures of vesicourethral anastomosis performed with intracorporeal suturing in a simulator and conventional suturing ex vivo in canine cadaveric tissue
Ahmed Hafez 2022
leak pressures for vesicourethral anastomosis with intracorporeal suturing, ex vivo
- no difference to conventional sutures
- potential for laparoscopic radical prostatectomy
Stans 2020 – review of prostatectomy for prostatic neoplasia
- survival outcome: 32-231d combined with adjunct treatments
- total prostatectomy may extend survival as a palliative treatment
- complications: urinary incontinence 33-100%
- evidence insufficient to suggest survival benefit over less invasive treatments as a sole tx
Iizuka 2022 – medical vs surgical treatment of prostatic adenocarcinoma
- prostatocystectomy performed with placement of bilateral SUB with distant stent located
in the distal urethra
- MST: surgery 337d longer than non-surgical 90.5d
- longer for total prostatectomy (510d) vs prostatocystectomy (83d)
- incontinence: total prostatectomy 50% mild, 30% severe
prostatocystectomy 100% severe
BMC
