Surgery MCQs Q6

A 76-year-old man presents with being “off his legs”. He reports a 3-month history of back pain. On examination:

• Lower limb weakness
• Loss of perineal sensation
• Large, hard, craggy prostate

Biochemistry shows PSA: 20 ng/mL.

What is the most likely diagnosis?

A. Metastatic prostate cancer

B. Benign prostatic hypertrophy

C. Chronic prostatitis

D. Obstructive uropathy

E. Prostatic abscess

✅ Correct Answer:

A. Metastatic Prostate Cancer

🔍 Decoding the Stem

• 💡 CLUE 1: Age 76, male → Risk factor for prostate malignancy
• 💡 CLUE 2: Clinical features (Back pain, Lower limb weakness, Loss of perineal sensation) → Suggests spinal cord compression → often due to bony metastasis
• 💡 CLUE 3: Prostate exam (Large, hard, craggy prostate) → classic for malignancy
• 💡 CLUE 4: PSA 20 ng/mL (Elevated above normal < 4 ng/mL) → supports prostate cancer

Why Metastatic Prostate Cancer is Correct

Most common malignant tumor in elderly men. Often presents with bone metastases, especially lumbar spine, causing back pain, lower limb weakness/paraplegia, and loss of perineal sensation if cauda equina involvement. PSA >10 ng/mL strongly suggests clinically significant prostate cancer. On digital rectal exam: hard, irregular, nodular (craggy) prostate is typical.

Why Other Options Are Incorrect

B. Benign prostatic hypertrophy (BPH): Usually causes urinary obstructive symptoms, not spinal cord compression. Prostate is smooth and enlarged, not hard or nodular.

C. Chronic prostatitis: Presents with painful urination, pelvic pain, and sometimes fever, not neurological deficits. PSA may be mildly elevated.

D. Obstructive uropathy: Can cause hydronephrosis, renal failure, urinary symptoms. Does not cause spinal cord compression or neurological deficits.

E. Prostatic abscess: Presents with fever, dysuria, perineal pain. Rare in elderly men, does not cause hard craggy prostate or neurological signs.

🧠 High-Yield Points

Older male + back pain + neurological deficit → consider metastatic prostate cancer
Craggy prostate + PSA >20 ng/mL → diagnostic clue
Common metastasis sites → lumbar spine, pelvis, ribs

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💡 Quick Clinical Challenge:

This patient requires urgent imaging to confirm the site of suspected cord compression.

Your Challenge:

1. What is the gold-standard imaging modality for suspected spinal cord compression?
2. Which bone-specific scan is typically used to stage prostate cancer metastasis?

Show Answer

✅ Answer:

1. MRI Spine.
2. Technetium-99m Bone Scan (Radionuclide bone scintigraphy).