Melanoma Diagnosis & Biopsy

In short

If melanoma is possible, the lesion is removed with a margin and examined under a microscope. Breslow thickness — how deep it has grown — guides the next operation and whether a sentinel lymph node biopsy is discussed. Dermoscopy helps decide what to remove. Do not have a suspected melanoma shaved off. This is general information, not a diagnosis.

Speed matters. A two-week-wait dermatology referral is how NHS GPs send changing moles.

What is Breslow thickness?

It is the depth of the melanoma in millimetres. Thinner melanomas have a better outlook. It is measured by a pathologist, not by looking at the skin.

What is a sentinel node biopsy?

A test to see if the first draining lymph node contains melanoma cells. It is used for staging some intermediate-thickness melanomas. It is not always required.

Help a patient afford cancer care

Gifts go to the Cancer Emergency Appeal’s wider fund for patients who cannot pay. They do not buy a guaranteed treatment or result.

Donate to cancer care

Do I need CT or PET scans?

Not for most thin melanomas. Scans are used if there is a higher chance of spread. Your letter will say.

Key takeaways

Excision biopsy confirms melanoma and measures depth.
Thickness drives the next steps.
Not every patient needs whole-body scans.

Care like this is out of reach for millions

The diagnosis, screening and treatment described here are routine in the UK. In Pakistan, Indonesia and Malaysia, poverty can put them out of reach. The Cancer Emergency Appeal raises funds towards clinically recommended care for patients who cannot pay; gifts go to the wider fund and do not buy a guaranteed treatment or result.

£50 towards supportive medicines £150 towards diagnostic tests £250 towards diagnosis and treatment £500 towards recommended treatment

Donate to cancer care View Cancer Emergency Appeal

Frequently asked questions

Why a second operation after the biopsy?

A wider margin of skin is taken to reduce the chance of leftover cells. That is standard, not a sign the first operation failed.

Can a blood test detect melanoma?

Not as a screening test for well people.

Does WAN diagnose melanoma in the UK?

No.

Back to the full melanoma guide

Editorial summary of published sources. A named oncology clinician has not signed off this guide. Use it to prepare questions for your healthcare team, not to diagnose symptoms or choose treatment. Editorial responsibility: Kaiser Khan. Updated 4 October 2026.