From the Guidelines
The recommended surgical margins for melanoma excision are 0.5-1 cm for in situ melanomas, 1 cm for thin melanomas (≤1 mm thickness), 1-2 cm for intermediate thickness melanomas (1-2 mm), and 2 cm for thick melanomas (>2 mm), as stated in the most recent and highest quality study 1.
Key Considerations
- The goal of surgical excision is to remove any potential microscopic tumor extensions while minimizing unnecessary tissue removal.
- Wider margins do not improve survival for thin melanomas but are necessary for thicker tumors due to their higher risk of local recurrence.
- The excision should extend down to the fascia in most cases.
- Mohs surgery may be considered for melanomas in cosmetically sensitive areas.
Evidence-Based Recommendations
- For in situ melanomas, a measured margin of 0.5 cm around the visible lesion should be obtained 2.
- For large in situ lentigo maligna melanoma, surgical margins greater than 0.5 cm may be necessary to achieve histologically negative margins 2.
- For patients with stage IA melanoma (≤ 1.0 mm), wide excision with a 1.0-cm margin is recommended (category 1) 2.
Important Notes
- The clinical/surgical margins discussed in this section refer to those taken at surgery and do not necessarily correlate with gross pathologic/histologic margins measured by pathologists 2.
- If margins are positive on final pathology, re-excision to achieve appropriate margins is necessary.
- A systematic review and meta-analysis also reported that surgical excision margins no more than 2.0 cm are adequate, and that surgical margins should not be less than 1.0 cm around primary melanoma 3.
From the Research
Margins for Melanoma Excision
- The recommended margins for melanoma excision have changed over time, with current guidelines suggesting a margin of 1-2 cm for invasive melanoma, depending on the thickness of the melanoma 4, 5.
- For melanoma in situ, a margin of 0.5-1 cm is recommended, with increasing evidence suggesting a 1 cm margin, particularly for those presenting on the head and neck in the setting of chronic sun damage 5.
- The choice of margin may depend on the location of the melanoma, with wider margins recommended for melanomas on the head, neck, hands, and feet 6.
- Studies have shown that narrower margins (1 cm) may be as safe as wider margins (2 cm) for melanomas thicker than 2 mm, with no significant difference in local or distant metastases and overall survival 7.
- Pathologic excision margins of less than 8 mm (equivalent to 1 cm in vivo) have been associated with poorer prognosis in terms of disease-free survival, while margins of 8-16 mm (equivalent to 1-2 cm in vivo) have shown no differences in survival outcomes 8.
Factors Influencing Margin Choice
- Tumor thickness: thicker tumors may require wider margins 4, 5.
- Location: melanomas on the head, neck, hands, and feet may require wider margins 6.
- Presence of ulceration: melanomas with ulceration may require wider margins 4.
- Deep margin: the deep margin has been shown to be an independent predictor of local and in-transit recurrence-free survival 8.
Surgical Techniques
- Wide excision: the main surgical treatment for invasive malignant melanoma, with examination of the sentinel node and complete lymph node dissection in selected cases 4.
- Mohs micrographic surgery: a useful alternative to standard surgery when more narrow margins are desired, particularly for melanomas on the head, neck, hands, and feet, or melanomas larger than 2.5 cm in diameter 6.
- Sentinel lymph node biopsy: provides relevant information for melanoma staging and is consistently recommended for melanomas >1-4 mm and highly recommended for melanomas >4 mm 5.