When is a unilateral inguinal lymph node dissection (LN dissection) indicated in vulvar carcinoma?

Unilateral Inguinal Lymph Node Dissection in Vulvar Carcinoma

Unilateral inguinal lymph node dissection is indicated in vulvar carcinoma when the primary tumor is lateralized (≥2 cm from vulvar midline), with >1 mm invasion, and clinically negative groin nodes. 1

Indications for Unilateral vs. Bilateral Node Dissection

Unilateral Node Dissection is Indicated When:

• Primary tumor is lateralized (≥2 cm from vulvar midline) 1
• Tumor has >1 mm invasion (stage IB or select stage II) 1
• Clinically negative inguinofemoral lymph nodes 1
• Unifocal tumor <4 cm in diameter 1

Bilateral Node Dissection is Required When:

• Tumor is within 2 cm of vulvar midline or crosses midline 1
• Tumor is anterior or posterior central 1
• Midline tumors with bilateral clinical node involvement 1

Sentinel Lymph Node Biopsy Considerations

For eligible patients, sentinel lymph node (SLN) biopsy can be performed instead of complete lymphadenectomy:

• SLN biopsy candidates: clinically negative nodes, unifocal tumor <4 cm, no previous vulvar surgery 1
• If SLN is not detected, proceed with ipsilateral inguinofemoral lymphadenectomy 1
• For lateralized tumors with unilateral SLN metastasis, unilateral groin treatment (either lymphadenectomy or radiation) is acceptable 1
• For midline tumors with unilateral SLN metastasis, unilateral groin treatment can be performed if contralateral groin has negative SLN or negative inguinofemoral lymphadenectomy 1

Special Considerations

• Risk of contralateral lymph node metastases in patients with early-stage vulvar cancer and unilateral metastatic SLN is low (2.9%), making unilateral treatment safe in most cases 2
• No contralateral SLNs are typically identified in patients with lateral vulvar lesions (>1 cm from midline) 3
• The risk of lymphedema after complete inguinofemoral lymphadenectomy is 30-70%, compared to only 5% with SLN biopsy 4, 5
• Wound complications occur in 20-40% of patients undergoing complete inguinofemoral lymphadenectomy 1, 4
• Subsequent groin relapses after inadequate initial treatment are rarely amenable to successful secondary treatment, emphasizing the importance of appropriate initial management 1, 5

Treatment Algorithm

1. For stage IA tumors (≤1 mm invasion): Simple partial vulvectomy without lymph node evaluation 1
2. For stage IB/II tumors (>1 mm invasion):
   • If lateralized (≥2 cm from midline): Radical partial vulvectomy with ipsilateral inguinofemoral lymph node evaluation 1
   • If central or near midline (<2 cm): Radical partial vulvectomy with bilateral inguinofemoral lymph node evaluation 1
3. For eligible patients, SLN biopsy can replace complete lymphadenectomy 1
4. If SLN is positive: Complete ipsilateral inguinofemoral lymphadenectomy or radiation 1

Pitfalls to Avoid

• Performing bilateral lymphadenectomy for all vulvar cancers regardless of location increases morbidity without improving outcomes 1, 4
• Superficial groin node dissection alone is not as safe as complete femoro-inguinal groin node dissection 6
• Up to 25% of patients with clinically negative lymph nodes may harbor micrometastases, highlighting the importance of appropriate nodal staging 5
• Omitting lymph node evaluation in tumors with >1 mm invasion significantly increases risk of recurrence 1