Surgery MCQs Q7

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ANATOMY • SURGERY

A 70-year-old man presents with urinary hesitancy and weak stream. On examination, his prostate is enlarged and irregular on digital rectal examination. PSA is elevated. Biopsy confirms adenocarcinoma of the prostate.

What is the most common site of origin for carcinoma of the prostate?

A Anterior zone

B Transitional zone

C Central zone

D Peripheral zone

E Posterior zone

Peripheral Zone. Approximately 70–80% of prostate adenocarcinomas arise in the peripheral zone. This explains why digital rectal examination (DRE) is an effective screening tool, as this zone is directly palpable.

Decoding Clue

1

CLUE "Prostate carcinoma + Typical elderly presentation"

TRANS Asking for the anatomical origin zone of malignancy.

2

CLUE "Irregular on DRE"

TRANS This implies the tumor is located in the zone most accessible to the finger (Peripheral Zone).

Explanation

A. Anterior zone: Composed mainly of fibromuscular stroma with minimal glandular tissue; hence, cancer is very rare here.

B. Transitional zone: The classic site for Benign Prostatic Hyperplasia (BPH). It surrounds the urethra and causes obstructive symptoms.

C. Central zone: Surrounds the ejaculatory ducts; it is the site of origin for only ~1-5% of prostate cancers.

E. Posterior zone: This is a descriptive term often used for the posterior aspect of the peripheral zone, but not a distinct histological zone in McNeal's classification.

🧠 High-Yield Pearls

Zone	Association	Key Fact
Peripheral Zone	Prostate Cancer (70%)	Palpable on DRE
Transitional Zone	BPH	Urethral Compression
Central Zone	Ejaculatory Ducts	Rare site for cancer
Anterior Stroma	Fibromuscular	Non-glandular zone

Integrated Clinical Questions

1. Most common prostate pathology overall?

Answer: Benign Prostatic Hyperplasia (BPH).

2. Most common zone involved in BPH?

Answer: Transitional Zone.

3. Why is prostate cancer easily detected by DRE?

Answer: Because ~70% arise in the Peripheral Zone, which is posterior and accessible to palpation.

4. Most common histology of prostate cancer?

Answer: Adenocarcinoma.

5. Key tumor marker used for screening/monitoring?

Answer: PSA (Prostate-specific antigen).

⚡ Exam Pearls

• Peripheral = Carcinoma (P is for Palpable).
• Transitional = Hyperplasia (T is for Through the middle).
• Anterior zone is mostly fibromuscular stroma (no glands = no adenocarcinoma).

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