The preferred biopsy technique for the diagnosis of melanoma is excisional biopsy of the complete lesion with a 2 mm margin and depth extending to fat (NHMRC and Cancer Council)
Once the diagnosis has been made, re-excision of the lesion should be performed to achieve definitive treatment. Narrow peripheral margins on the initial diagnostic biopsy ensure potential staging investigations, such as sentinel lymph node biopsy (SLNB), are not disrupted.
The recommended surgical margins for excision of confirmed melanoma depend on the tumour’s Breslow thickness. The Breslow thickness is a measurement of the depth of invasion of the melanoma into the skin and is a critical factor in prognosis and management. Here are general recommendations for excision margins based on Breslow thickness:
- Melanoma in situ:
- Margins of 0.5 to 1 cm
- Melanomas ≤ 1 mm thick:
- Margins of 1 cm
- Melanomas 1.0–2.0 mm thick:
- Margins of 1-2 cm (the exact margin within this range may depend on other tumor characteristics and the location of the melanoma)
- Melanomas > 2.0 mm thick:
- Margins of 2 cm
Using a different reference (below). After the initial excision biopsy; the radial excision margins, measured clinically from the edge of the melanoma, be:
- 1. (pTis) Melanoma in situ: margin 5mm
- 2. (pT1) Melanoma < 1.0mm: margin 1cm
- 3. (pT2) Melanoma 1.0–2.0mm: margin 1–2cm
- 4. (pT3) Melanoma 2.0–4.0mm: margin 1–2cm
- 5. (pT4) Melanoma > 4.0mm: margin 2cm