What is the differential diagnosis for an intermittent lump on the anterior aspect of the testicle?

Differential Diagnosis for Intermittent Anterior Testicular Lump

An inguinal hernia is the most likely diagnosis for an intermittent lump on the anterior aspect of the testicle that comes and goes, particularly if it changes with position or Valsalva maneuver. 1

Primary Differential Considerations

Inguinal Hernia (Most Likely)

• Herniated bowel or omentum extending into the scrotum characteristically appears and disappears with positional changes or straining 1
• The intermittent nature strongly suggests reducible hernia content moving in and out of the scrotal compartment 1
• Duplex Doppler ultrasound can identify herniated bowel or omentum in the scrotum and differentiate this from intratesticular pathology 1

Varicocele (Second Most Common)

• Dilated pampiniform plexus veins become more prominent when standing and decompress when supine 1
• This creates the classic "bag of worms" sensation that appears and disappears with position 1
• More commonly affects the left hemiscrotum due to venous drainage patterns 2

Intermittent Testicular Torsion

• Can present with intermittent pain and swelling during torsion episodes, though typically painful when present 1
• Represents a surgical emergency requiring urgent evaluation even if symptoms resolve 3
• The testis may detorse spontaneously, creating an intermittent presentation 3

Less Common but Important Considerations

Extratesticular Benign Masses

• Spermatoceles and epididymal cysts are the most common scrotal findings (27% in one series), though these typically don't come and go 4
• Hydroceles (11% of scrotal masses) can occasionally fluctuate in size but rarely disappear completely 4
• These are usually palpable as separate from the testis itself 5, 4

Testicular Cancer (Critical to Exclude)

• While testicular tumors typically present as persistent painless masses, any intratesticular mass has approximately 90% likelihood of malignancy 4
• Patients with inguinal hernia history have increased testicular cancer risk (RR 1.37) 1
• The intermittent nature makes cancer less likely, but it cannot be excluded on clinical grounds alone 6, 4

Diagnostic Approach

First-Line Imaging

• Duplex Doppler ultrasound of the scrotum is the mandatory first-line imaging modality 3, 1
• Ultrasound is nearly 100% sensitive for detecting intrascrotal masses and 98-100% accurate for distinguishing intratesticular from extratesticular processes 3
• The examination must include both grayscale and color Doppler to assess blood flow patterns and identify the "whirlpool sign" of torsion if present 3

Key Ultrasound Findings to Identify

• Herniated bowel or omentum extending through the inguinal canal into the scrotum 1
• Varicocele with dilated veins >3mm that increase with Valsalva 1
• Intratesticular versus extratesticular location of any mass, as this fundamentally changes management 3, 4
• Testicular perfusion patterns to exclude torsion, which shows decreased or absent flow 3

Management Algorithm

If Hernia Confirmed

• Refer to general surgery for elective repair if asymptomatic 1
• Urgent surgical consultation if incarcerated or strangulated 3

If Varicocele Confirmed

• Most require no treatment unless associated with documented infertility or scrotal pain 2
• Refer to urology subspecialist for consideration of surgical management only if symptomatic or fertility concerns 2

If Intratesticular Mass Identified

• Immediate urologic referral for radical inguinal orchiectomy 3, 7
• Obtain tumor markers (AFP, β-HCG, LDH) before any intervention 3, 7
• Discuss sperm banking before therapeutic intervention in reproductive-age men 7

If Torsion Suspected

• Immediate surgical exploration within 6 hours of symptom onset to achieve >90% salvage rates 3
• Do not delay surgery for imaging if clinical suspicion is high 3

Critical Pitfalls to Avoid

• Never assume an intermittent lump is benign without ultrasound confirmation - testicular cancer can present atypically and delay in diagnosis correlates with higher stage at presentation 7
• Avoid scrotal approach for any suspected testicular tumor - this is associated with higher local recurrence rates and violates oncologic principles 7
• Do not rely on the Prehn sign alone to differentiate epididymitis from torsion, as it has poor sensitivity and specificity 3
• Never perform scrotal biopsy or scrotal incision for suspected malignancy - only inguinal orchiectomy is appropriate 3