Wide local excision

The second operation after a melanoma is diagnosed: removal of a measured margin of normal-looking skin and fat around the biopsy scar, down to the fascia, to clear any remaining cancer cells. The margin, 5 mm to 2 cm, is set by the Breslow thickness.

Related terms

• Condition

  Melanoma

  A cancer of the pigment-producing cells (melanocytes) of the skin. It is the most serious of the common skin cancers because it can spread to the lymph nodes and other organs; found early, it is usually cured by excision. New Zealand and Australia have the highest rates in the world.

• Glossary

  Surgical margin

  The rim of normal-looking tissue removed around a tumour so that its microscopic extensions are included. The clinical margin is measured on the skin before excision; the histological margin is the distance from the tumour to the cut edge under the microscope, usually reported as clear (at least 1 mm), close (under 1 mm) or involved.

• Investigation

  Breslow thickness

  The depth of a melanoma in millimetres, measured under the microscope from the top of the granular layer of the epidermis to its deepest point. Introduced by Alexander Breslow in 1970, it is the strongest single predictor of outcome and sets the width of the wide local excision and whether a sentinel node biopsy is offered.

Articles mentioning this term

1. Patient information · 26 September 2026

   Melanoma surgery

   Wide local excision and sentinel node biopsy after melanoma: why the margin follows Breslow thickness, what happens on the day, the risks and follow-up.

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