Skin: Excision margins by Breslow thickness
Free question published 28 July 2026
A 58-year-old man undergoes excision biopsy of a pigmented lesion on his back. Histology confirms a cutaneous melanoma with a Breslow thickness of 3.2 mm, no ulceration, and clear but narrow peripheral margins. Staging investigations show no nodal or distant disease (stage II). He is referred to discuss a wide local excision. What clinical excision margin is most appropriate?
- A3 cm
- B2 cm
- C5 cm
- D0.5 cm
- E1 cm
Why B is correct
NICE NG14 recommends a 2 cm clinical margin when excising stage II melanoma. This patient has a 3.2 mm (T3), non-ulcerated, node-negative melanoma, which is stage II, so a 2 cm wide local excision margin is correct.
And why the others are not
- AIncorrect: a 3 cm margin is not recommended by NICE and exceeds the evidence-based margin without added benefit.
- CIncorrect: 5 cm margins reflect historical practice and are not supported by NICE NG14 or modern margin trials.
- DIncorrect: a margin of at least 0.5 cm is for stage 0 (in situ) melanoma, not invasive stage II disease.
- EIncorrect: a 1 cm margin is used for stage I melanoma, or for stage II only where a 2 cm margin would cause unacceptable disfigurement or morbidity, which does not apply on the back.
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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