BPH in simple language for university exam

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Benign Prostatic Hyperplasia (BPH) - University Exam Notes

What is BPH?

BPH is the non-cancerous enlargement of the prostate gland due to overgrowth of both the glandular (epithelial) and stromal (fibromuscular) components. It is the most common benign disease of the male urinary tract and one of the most common conditions treated by urologists.

Normal prostate in young men: ~20 mL
In BPH: volume exceeds 30 mL (can reach 60-100 g, a 3- to 5-fold increase)
"Benign" means it does NOT spread or become cancer

Anatomy Reminder

The prostate has 4 zones: peripheral, central, transitional, and fibromuscular stroma. BPH arises specifically in the transitional zone (periurethral zone) - this is why it squeezes the urethra. Prostate cancer, by contrast, typically arises in the peripheral zone.

Sagittal diagram of prostate zones - Goldman-Cecil Medicine

Epidemiology

Age group	Prevalence of histological BPH
>50 years	~50%
60-69 years	~70%
80s	~90%

Of those with histological BPH, ~50% will develop symptomatic lower urinary tract symptoms (LUTS).

Key point: BPH is an age-related disease. It does NOT occur in men castrated before puberty or in men with conditions that block androgen action.

Pathogenesis (Why Does It Happen?)

The key hormone is Dihydrotestosterone (DHT):

Circulating testosterone enters prostate cells
The enzyme 5α-reductase type 2 converts testosterone → DHT
DHT is 10× more potent than testosterone
DHT binds nuclear androgen receptors → stimulates stromal cell proliferation and prevents epithelial cell death

Aging factor: As men age, testosterone levels fall but estrogen levels remain stable (or rise due to peripheral conversion). Estrogens act synergistically with DHT to further drive growth - both stromal and epithelial cells express estrogen receptors.

Think of it as: Too much DHT + estrogen effect = overgrowth of the prostate's inner (transitional) zone → squeezes the urethra like a fist squeezing a garden hose.

Pathology (What Does It Look Like?)

Gross:

Prostate weight 60-100 g (normal ~20 g)
Hyperplastic nodules seen on cross-section - may be solid or cystic
Urethra compressed to a slit-like orifice

Microscopic:

Nodules made of variable proportions of glands + fibromuscular stroma
Hyperplastic glands lined by two cell layers: tall columnar inner cells + flattened basal outer cells (KEY exam point - this distinguishes BPH from prostate carcinoma, which lacks the basal cell layer)
Glandular lumina may contain corpora amylacea (laminated protein secretions)

Symptoms (LUTS - Lower Urinary Tract Symptoms)

BPH causes symptoms through two mechanisms:

Mechanical obstruction - the enlarged gland physically compresses the urethra
Dynamic obstruction - smooth muscle in the prostate contracts, further narrowing the urethra

Symptoms are divided into three groups:

Voiding (Obstructive) Symptoms

Hesitancy (difficulty starting urination)
Weak/poor urine stream
Straining to void
Prolonged voiding time
Overflow dribbling

Storage (Irritative) Symptoms

Urinary frequency (needing to go often)
Urgency (sudden strong need to urinate)
Nocturia (waking at night to urinate)
Dysuria (painful urination)

Post-void Symptoms

Feeling of incomplete bladder emptying
Post-void dribbling

Exam note: Prostate size does NOT reliably correlate with severity of symptoms.

Complications (if untreated)

Complication	Mechanism
Bladder hypertrophy	Bladder muscle works harder against obstruction
Residual urine (incomplete emptying)	Increased infection risk (UTIs)
Acute urinary retention	Complete obstruction
Hydronephrosis	Back-pressure on kidneys from chronic obstruction
Recurrent UTIs (bladder + kidney)	Stagnant urine = bacterial culture medium

Diagnosis

History - LUTS symptoms, symptom scoring (International Prostate Symptom Score, IPSS)
Digital Rectal Exam (DRE) - prostate feels smooth and rubbery (unlike the hard, irregular feel of cancer)
Urinalysis - rule out infection
PSA (Prostate-Specific Antigen) - used in patients with >10-year life expectancy; BPH can mildly raise PSA
Post-void residual urine volume - measured by bladder ultrasound
Uroflowmetry - measures urine flow rate
Cystoscopy / Urodynamics - if initial evaluation is inconclusive

Treatment

Step 1 - Watchful Waiting + Lifestyle Changes

For mild symptoms. Reduce evening fluid intake, limit caffeine and alcohol, bladder training.

Step 2 - Medical Therapy

Drug Class	Examples	Mechanism	Side Effects
α1-blockers	Tamsulosin, Alfuzosin, Doxazosin	Relax smooth muscle in prostate/bladder neck → reduce outflow resistance	Dizziness (orthostasis), retrograde ejaculation, rhinitis
5α-reductase inhibitors	Finasteride, Dutasteride	Block testosterone → DHT conversion → shrink prostate over months	Reduces serum PSA by ~50% (important for cancer screening interpretation), sexual side effects
Combination	α1-blocker + 5α-RI	Synergistic effect, best for large prostates	Combined side effects
Muscarinic antagonists	Oxybutynin	Target overactive bladder/storage symptoms	Dry mouth, constipation

Key exam point: 5α-reductase inhibitors work slowly (months) but actually shrink the gland; α1-blockers work fast but only relax muscle without shrinking the gland.

Step 3 - Surgical / Minimally Invasive (for refractory cases)

TURP (Transurethral Resection of the Prostate) - the gold standard surgery; "reaming out" the inner gland through a scope
Laser therapy (HoLEP, GreenLight laser)
HIFU (High-Intensity Focused Ultrasound)
Transurethral electrovaporization
Radiofrequency ablation
Simple open prostatectomy - for very large glands (>100 g)

BPH vs Prostate Cancer - Key Differences (High-Yield Exam Table)

Feature	BPH	Prostate Cancer
Zone of origin	Transitional zone	Peripheral zone
Nature	Benign (non-invasive)	Malignant
DRE	Smooth, rubbery, enlarged	Hard, irregular nodule
PSA	Mildly elevated	Often significantly elevated
Histology	Two cell layers (columnar + basal)	Lacks basal cell layer
Treatment goal	Symptom relief	Cure / disease control

Quick Summary for Revision

What: Non-cancerous enlargement of prostate (transitional zone)
Who: Men >50, incidence rises with age
Why: DHT (from testosterone via 5α-reductase) + estrogen in older men
Where: Transitional zone → compresses urethra → LUTS
Symptoms: Hesitancy, weak stream, frequency, nocturia, incomplete emptying
Diagnose: IPSS score, DRE, PSA, flow rate, post-void residual
Treat: Lifestyle → α1-blockers / 5α-RI → TURP if needed

Sources: Robbins & Kumar Basic Pathology, 10th ed.; Goldman-Cecil Medicine; Sabiston Textbook of Surgery, 27th ed.; Campbell Walsh Wein Urology

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