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Skin: Wide local excision margin for thin melanoma

Free question published 13 October 2026

SkinWide local excision margin for thin melanoma

A 35-year-old woman has an excision biopsy of a forearm lesion reported as a melanoma with a Breslow thickness of 0.7 mm, no ulceration, and clear narrow margins. Staging shows no nodal or distant disease, confirming stage I disease. She is referred for a wide local excision. What clinical excision margin is most appropriate?

  1. A2 cm
  2. B1 cm
  3. C0.5 cm
  4. D4 cm
  5. E3 cm

Why B is correct

NICE NG14 recommends a 1 cm clinical margin when excising stage I melanoma (or where a 2 cm margin would cause unacceptable disfigurement or morbidity). This 0.7 mm, non-ulcerated, node-negative tumour is stage I, so a 1 cm wide local excision margin is correct.

And why the others are not

  • AIncorrect: a 2 cm margin is reserved for stage II melanoma.
  • CIncorrect: a margin of at least 0.5 cm applies to stage 0 (in situ) melanoma, not invasive stage I disease.
  • DIncorrect: a 4 cm margin reflects obsolete practice and is not supported by NG14.
  • EIncorrect: a 3 cm margin is not recommended by NICE and exceeds the evidence base.

Source NICE NG14 - Melanoma: assessment and management — National Institute for Health and Care Excellence. Melanoma: assessment and management. NICE guideline NG14. Published 29 July 2015, updated 2022.

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