The prostate: • Walnut-shaped gland surrounds the urethra. • Prostate weights about 20g. • Measures about 4 X3X2. • Apex = inferior portion of prostate. • Base = superior portion and continuous with bladder neck.
Lobes of the Prostate • Anterior lobe • Median lobe • Two lateral lobes • Posterior lobe Image Source: SEER Training Website
* Histology of the prostate: • The prostatic gland consists of glandular component and fibromuscular stroma. • The glandular component is formed of prostatic acini arranged in lobules. The acini are highly folded and lined by epithelial cells. The percentage of glandular tissue vary between the different zones of the gland.
Prostate zones * Central zone (CZ): • Cone shaped region that surround the ejaculatory ducts (extends from bladder base to the verumontanum) • Accounts for 25% of glandular tissue. * Peripheral zone (PZ): • Posterolateral prostate • Accounts for the majority of glandular tissue. • The site of prostate adenocarcinoma
* Transitional zone (TZ): • Surrounds the prostatic urethra proximal to the verumontanum • Accounts for only 5-10% of glandular tissue.
* Functions of the prostate: Secretes prostatic secretions. During orgasm, prostate muscles contract and propel ejaculate out of the penis n n
* Causes BPH: BPH is part of the natural aging process, like getting gray hair or wearing glasses BPH cannot be prevented BPH can be treated n n n
* Proposed Etiologies of BPH: • The causes of benign prostatic hyperplasia are not fully understood. Several theories have been proposed to explain BPH, the most accepted one is hormonal changes.
Estrogen: may play a role in BPH. As men age, testosterone levels drop, and the proportion of estrogen increases, possibly triggering prostate growth. • In addition to the mechanical effects of the enlarged prostate, clinical symptoms of lower urinary tract obstruction are also due to smooth muscle-mediated contraction of the prostate. The tension of prostate smooth muscle is mediated by the α1-adrenoreceptor localized to the prostatic stroma.
* Morphological features of BPH: * Gross Findings: • The periurethral part of the gland is most commonly involved. • Overall, the gland is enlarged, often reaching massive size, and has a firm, rubbery consistency. Small nodules are present throughout the gland, usually 0.5–1 cm in diameter but sometimes much larger. Some of the larger nodules show cystic change. • The urethra appears slit-like and compressed.
* Microscopic Findings: • The nodules are composed of a variable mixture of hyperplastic glandular elements and hyperplastic stromal muscle. The glands are larger than normal and lined by tall epithelium that is frequently thrown into papillary projections.
* Clinical Course: • Symptoms of nodular hyperplasia, when present, relate to two secondary effects: 1. Compression of the urethra with difficulty in urination. 2. Retention of urine in the bladder with subsequent distention and hypertrophy of the bladder, infection of the urine, and development of cystitis and renal infections. * Symptoms: Patients experience frequency, nocturia, difficulty in starting and stopping the stream of urine, overflow dribbling, and dysuria (painful micturition). In many cases, sudden, acute urinary retention appears for unknown reasons and persists until the patient receives emergency catheterization.
In addition to these difficulties in urination, prostatic enlargement results in the inability to empty the bladder completely, so a considerable amount of residual urine is left. This residual urine provides a static fluid that is vulnerable to infection. On this basis, catheterization or surgical manipulation provides a real danger of the introduction of organisms and the development of pyelonephritis.
Many secondary changes occur in the bladder, such as hypertrophy and diverticulum formation. Hydronephrosis or acute retention, with secondary urinary tract infection and even uremia, may develop. • BPH is not considered to be a premalignant lesion.
* Treatment of BPH: A. Mild cases: • May be treated without medical or surgical therapy, by decreasing fluid intake, especially prior to bedtime; moderating the intake of alcohol and caffeine-containing products; and following timed voiding schedules. The most commonly used and effective medical therapy for symptoms relating to benign hyperplasia are α-blockers, which decrease prostate smooth muscle tone via inhibition of α1-adrenergic receptors.
B. Moderate to severe cases: • With no response to medical therapy, a wide range of more invasive procedures exists. • Transurethral resection of the prostate (TURP). It is indicated as a first line of therapy in certain circumstances, such as recurrent urinary retention. • Laser therapy.
TURP (Transurethral resection of the prostate) • Uses an electrical “knife” to surgically cut and remove excess prostate tissue • Effective in relieving symptoms and restoring urine flow.
C. Open prostatectomy • “Too large prostate” -- >100 gm • Combined with bladder diverticulum or vesical stone surgery
References: Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition.