What is a good margin for resection in a patient with melanoma?

Melanoma Resection Margins

For melanoma resection, use thickness-based margins: 0.5 cm for in situ disease, 1 cm for melanomas ≤1.0 mm, 1-2 cm for melanomas 1.01-2.0 mm, and 2 cm for melanomas >2.0 mm thick. 1

Margin Recommendations by Breslow Thickness

Melanoma In Situ

• Use 0.5 cm margins for standard melanoma in situ 2, 1
• For lentigo maligna melanoma, particularly on the head and neck, margins greater than 0.5 cm may be necessary to achieve histologically negative margins due to unpredictable subclinical extension that can extend several centimeters beyond visible borders 2, 1
• Approximately 50% of melanoma in situ on the head and neck require margins exceeding 0.5 cm for complete clearance 1

Thin Melanomas (≤1.0 mm)

• Use 1 cm margins (Category 1 recommendation) 2, 1
• Multiple prospective randomized trials, including the WHO study of 612 patients, demonstrated that 1 cm margins provide equivalent local recurrence rates, disease-free survival, and overall survival compared to 3 cm margins at 90-month median follow-up 2

Intermediate Melanomas (1.01-2.0 mm)

• Use 1-2 cm margins (Category 1 recommendation) 2, 1
• The narrower 1 cm margin is supported by strong evidence showing no difference in local recurrence (2.0% vs 2.1%), disease-specific survival (87% vs 85% at 5 years), or overall outcomes compared to 2 cm margins 3
• The Swedish Melanoma Study Group trial of 769 patients with median 5.8-year follow-up found no significant differences in local recurrence, regional recurrence, or survival between 2 cm and 5 cm margins 4
• Consider 1 cm margins for head/neck and extremity locations where cosmetic and functional outcomes matter, as 32.5% of head/neck and 48.7% of extremity patients successfully used 1 cm margins without increased recurrence 3

Thick Melanomas (>2.0 mm)

• Use 2 cm margins for all melanomas >2.0 mm thick 2, 1
• This is a Category 1 recommendation for tumors ≤4.0 mm and Category 2A for tumors >4.0 mm 2, 1
• The National Intergroup Trial of 468 patients demonstrated no differences in local recurrence, disease-free survival, or overall survival between 2 cm and 4 cm margins at 10-year median follow-up 2
• A prospective randomized trial comparing 1 cm versus 3 cm margins for melanomas >2.0 mm showed wider margins had slightly lower combined local/regional/nodal recurrence but no improvement in melanoma-specific survival 2, 1

Anatomic and Practical Modifications

Difficult Anatomic Sites

• Margins of 1.0-2.0 cm are acceptable in anatomically challenging areas where achieving a full 2 cm margin would be difficult 2, 1
• Surgical margins may be modified for individual anatomic or cosmetic considerations without compromising oncologic outcomes 2
• On the head and neck, using 1 cm margins instead of 2 cm significantly reduces the need for grafts or flaps (p=0.025) 3

Special Surgical Techniques

• For lentigo maligna melanoma, consider Mohs micrographic surgery or staged excision with meticulous margin control, which have shown high local control rates 2, 1
• These techniques are particularly valuable for cosmetically sensitive areas, though not universally accepted 2

Critical Timing Considerations

• Perform wide local excision within 2-6 weeks after biopsy to allow complete pathologic assessment and coordinate sentinel lymph node biopsy when indicated 5
• Sentinel lymph node biopsy must be performed before wide excision whenever possible to avoid disrupting lymphatic drainage patterns 5

Common Pitfalls to Avoid

• Do not use margins less than 1 cm for invasive melanoma (except 0.5 cm for in situ disease), as systematic reviews confirm this increases recurrence risk 2, 1
• Do not assume initial biopsy depth is accurate—shallow biopsies may underestimate true Breslow depth, potentially leading to inadequate surgical planning 5
• Do not routinely use margins exceeding 2 cm for any melanoma, as no survival benefit has been demonstrated and morbidity increases 6, 7
• For melanomas with tumor regression on histology, use margins for the category immediately above the actual thickness 2
• Remember that clinical/surgical margins taken at surgery do not necessarily correlate with gross pathologic/histologic margins measured by pathologists 2, 1