Scrotal Mass: MCCQE1 Preparation Guide

Introduction

The evaluation of a scrotal mass is a high-yield topic for the MCCQE1 and is a core competency under the Medical Council of Canada (MCC) objectives (Objective 78-4). The presentation can range from a benign, painless cyst to a surgical emergency like testicular torsion, or a life-threatening malignancy.

As a Medical Expert (CanMEDS), the Canadian physician must effectively differentiate between solid and cystic lesions, painful and painless presentations, and identifying “red flags” requiring urgent urological referral.

Clinical Approach to Scrotal Mass

The initial assessment determines the urgency of the situation. Is this an acute scrotum (painful, emergency) or a chronic mass (painless, elective/urgent)?

Differential Diagnosis

The differential diagnosis is best categorized by the nature of the mass and the presence of pain.

Key Conditions & Management

1. Testicular Carcinoma

This is the “cannot miss” diagnosis for MCCQE1.

• Risk Factors: Cryptorchidism (most significant), Klinefelter syndrome, family history, Caucasian race.
• Histology:
  • Seminoma: Most common, radiosensitive, better prognosis.
  • Non-Seminomatous Germ Cell Tumors (NSGCT): Embryonal, Teratoma, Choriocarcinoma, Yolk Sac.
• Tumor Markers:

// Key Tumor Markers for MCCQE1
const markers = {
  AFP: "Alpha-fetoprotein (Elevated in NSGCT, never in pure Seminoma)",
  bHCG: "Beta-Human Chorionic Gonadotropin (Elevated in both Seminoma and NSGCT)",
  LDH: "Lactate Dehydrogenase (Non-specific marker of tumor burden)"
};

2. Varicocele

• Pathophysiology: Valvular incompetence of the spermatic vein.
• Significance: Most common cause of surgically correctable male infertility.
• Red Flag: A Right-sided varicocele (or a varicocele that does not decompress when supine) warrants abdominal imaging (CT/US) to rule out retroperitoneal pathology (e.g., Renal Cell Carcinoma with IVC thrombus).

3. Testicular Torsion

• Diagnosis: Clinical. Doppler US can confirm but should not delay surgical exploration if clinical suspicion is high.
• Management: Immediate surgical exploration, detorsion, and bilateral orchiopexy.

Investigations

Laboratory

• Urinalysis & Culture: To rule out UTI/Epididymitis.
• STI Swabs: If sexually active/discharge present.
• Tumor Markers: AFP, b-HCG, LDH (if solid mass found).

Imaging

• Scrotal Ultrasound with Doppler: The Gold Standard initial imaging modality for any scrotal mass. It differentiates solid vs. cystic and intratesticular vs. extratesticular.
• CT Abdomen/Pelvis: Staging for testicular cancer (metastasis to retroperitoneal lymph nodes).

Comparison of Common Scrotal Masses

Canadian Guidelines & Choosing Wisely

CUA (Canadian Urological Association) Guidelines

1. Testicular Cancer: Any solid intratesticular mass on ultrasound is malignant until proven otherwise. Referral to a urologist should be urgent (typically seen within 2 weeks).
2. Imaging: Choosing Wisely Canada recommends against ordering a CT scan for the initial workup of a scrotal mass; Ultrasound is the diagnostic modality of choice.
3. Fertility Preservation: Canadian guidelines emphasize offering sperm banking to all men undergoing orchiectomy for testicular cancer prior to chemotherapy or radiation.

Antibiotic Stewardship (Epididymitis)

Treatment guidelines in Canada generally follow local resistance patterns:

• STI (Gonorrhea/Chlamydia): Ceftriaxone 250-500mg IM x1 + Doxycycline 100mg BID x 10-14 days.
• Enteric Organisms: Fluoroquinolones (e.g., Levofloxacin) are often used, but be aware of rising E. coli resistance in Canada. Septra (TMP-SMX) is an alternative if susceptibility is known.

Key Points to Remember for MCCQE1

• Ultrasound First: The answer to “What is the best initial diagnostic step?” for a scrotal mass is almost always Scrotal Ultrasound.
• Biopsy Contraindicated: Do not biopsy testicular masses.
• Right-Sided Varicocele: Investigate the retroperitoneum/kidney.
• Torsion vs. Epididymitis:
  • Torsion: Sudden onset, absent cremasteric reflex, negative Prehn’s.
  • Epididymitis: Gradual onset, fever, dysuria, positive Prehn’s.
• Lymphatic Drainage: Testes drain to Para-aortic (Retroperitoneal) nodes. Scrotal skin drains to Inguinal nodes. This is why transscrotal biopsy is bad (changes drainage).

Sample Question

Scenario A 24-year-old male presents to his family physician complaining of a painless lump in his right scrotum that he noticed while showering 3 days ago. He reports a sensation of “heaviness” in the scrotum but denies fever, dysuria, or penile discharge. He has no significant past medical history. Physical examination reveals a firm, non-tender, 2 cm nodule on the anterior aspect of the right testicle. The mass does not transilluminate. The left testicle is unremarkable. There is no inguinal lymphadenopathy.

Which one of the following is the most appropriate next step in management?

• A. Reassurance and follow-up in 3 months
• B. Course of empirical antibiotics for epididymitis
• C. Scrotal ultrasound with Doppler
• D. Fine needle aspiration biopsy of the nodule
• E. CT scan of the abdomen and pelvis

Explanation

The correct answer is:

• C. Scrotal ultrasound with Doppler

Detailed Explanation: This clinical scenario is highly suspicious for testicular cancer. The patient is in the peak age group (15-35) and presents with a classic painless, firm, intratesticular nodule.

• Option C (Correct): Scrotal ultrasound is the gold standard initial imaging modality to confirm the presence of a solid intratesticular mass and distinguish it from benign cystic lesions (like hydroceles) or extratesticular pathology.
• Option A (Incorrect): A solid testicular mass in a young male is malignancy until proven otherwise. Delaying diagnosis by 3 months is negligent and could affect prognosis.
• Option B (Incorrect): Antibiotics are indicated for epididymitis, which typically presents with pain, fever, and dysuria. This patient has a painless mass and no signs of infection.
• Option D (Incorrect): Transscrotal biopsy is contraindicated in suspected testicular cancer due to the risk of tumor seeding and altering lymphatic drainage patterns. Diagnosis is confirmed via radical inguinal orchiectomy after ultrasound and marker evaluation.
• Option E (Incorrect): While CT abdomen/pelvis is used for staging (checking for retroperitoneal lymphadenopathy), it is not the initial diagnostic step. Ultrasound confirms the primary lesion first.

References

1. Canadian Urological Association (CUA). (2019). Guideline on Testicular Cancer. Retrieved from CUA.org.
2. Medical Council of Canada. Objectives for the Qualifying Examination (MCCQE) Part I. Objective 78-4: Scrotal Mass/Pain.
3. Toronto Notes 2024. Urology Chapter: Scrotal Mass & Testicular Cancer.
4. Baird, D.C., et al. (2019). Acute Scrotum: Evaluation and Management. American Family Physician.
5. Choosing Wisely Canada. Urology Recommendations.