- Candidates for SLN biopsy include:
- Patients with newly diagnosed clinically node-negative primary cutaneous melanoma:
- Who are predicted to be at intermediate or high risk of harboring occult regional nodal disease based on primary tumor characteristics
- Many melanoma clinicians consider a threshold risk of a positive SLN:
- Of at least 5% to be sufficient in an otherwise healthy individual to offer lymphatic mapping and sentinel node biopsy
- Patients with newly diagnosed clinically node-negative primary cutaneous melanoma:
- Although uniform risk thresholds have not been completely resolved:
- A tumor thickness threshold for SLN of at least 0.8 mm or for tumors < 0.8 mm with ulceration or other high-risk features, including:
- Lymphovascular invasion or high mitotic rate:
- Particularly when associated with young age:
- Can be considered for SLNB
- Particularly when associated with young age:
- The Melanoma Institute Australia SLN metastasis risk prediction tool may also be referenced as a useful guide to estimate individual risk of harboring a tumor-involved SLN:
Reference: NCCN Guidelines for Melanoma, Version 2.2024
- Technical Considerations:
- Performed using preoperative lymphoscintigraphy and intraoperative blue dye and / or radiotracer
- Nodes identified are sent for detailed histologic and immunohistochemical analysis
- Special Scenarios:
- Head & Neck Melanoma:
- SLNB feasible but technically challenging:
- Should be done in experienced centers
- SLNB feasible but technically challenging:
- Acral Lentiginous Melanoma:
- SLNB recommended if ≥ 1 mm or high-risk features present
- Elderly Patients:
- Consider individual comorbidities and life expectancy
- Age alone is not a contraindication
- Head & Neck Melanoma:
- Contraindications to SLNB:
- Clinically or radiographically positive nodes
- Medical unfitness for anesthesia / surgery
- Limited life expectancy or competing risks that outweigh benefit
- Prognostic Value:
- SLN status is the strongest predictor of survival in clinically node-negative melanoma
- SLNB guides adjuvant systemic therapy decisions
- References:
- Morton DL et al., N Engl J Med. 2006;355(13):1307–1317.
- Faries MB et al., N Engl J Med. 2017;376(23):2211–2222.
- Gershenwald JE et al., CA Cancer J Clin. 2017;67(6):472–492.
- Follow-Up:
- SLN-negative:
- Routine clinical and imaging surveillance
- SLN-positive:
- Consider adjuvant immunotherapy or targeted therapy
- Imaging surveillance recommended
- SLN-negative:
- Conclusion:
- SLNB is a vital component of melanoma management for accurate staging and treatment guidance
- It should be offered to patients based on tumor thickness and high-risk features, per NCCN and international consensus guidelines
Rodrigo Arrangoiz MS, MD, FACS, FSSO 