Melanoma - Diagnosing melanoma

A diagnosis of melanoma will usually begin with an examination of your skin. Your GP will refer you to a specialist if they suspect melanoma.

Some GPs take digital photographs of suspected tumours so they can email them to a specialist for assessment.

As melanoma is a relatively rare condition, many GPs will only see a case every few years. It's important to monitor your moles and return to your GP if you notice any changes. Taking photos to document any changes will help with diagnosis.

Seeing a specialist

You will be referred to a dermatology clinic or hospital for further testing if melanoma is suspected. You should see a specialist within two weeks of seeing your GP.

The dermatologist or plastic surgeon will examine the mole and the rest of your skin. They may also remove the mole and send it for testing (biopsy) to check whether the mole is cancerous. A biopsy is usually carried out under local anaesthetic, meaning the area around the mole will be numbed and you won't feel any pain.

If cancer is confirmed, you will usually need a further operation, most often carried out by a plastic surgeon, to remove a wider area of skin.

Further tests

Further tests will be carried out if there is a concern the cancer has spread into other organs, bones or your bloodstream.

Sentinel lymph node biopsy

If melanoma spreads, it will usually begin spreading through channels in the skin (called lymphatics) to the nearest group of glands (called lymph nodes). Lymph nodes are part of the body’s immune system, helping to remove unwanted bacteria and particles from the body.

Sentinel lymph node biopsy is a test to determine whether microscopic amounts of melanoma (less than would show up on any X-ray or scan) might have spread to the lymph nodes. It is usually carried out by a specialist plastic surgeon, while you are under general anaesthetic.

A combination of blue dye and a weak radioactive chemical is injected around your scar. This is usually done just before the wider area of skin is removed. The solution follows the same channels in the skin as any melanoma.

The first lymph node this reaches is known as the “sentinel” lymph node. The surgeon can locate and remove the sentinel node, leaving the others intact. The node is then examined for microscopic specks of melanoma (this process can take several weeks).

If the sentinel lymph node is clear of melanoma, it's extremely unlikely that any other lymph nodes are affected. This can be reassuring because if melanoma spreads to the lymph nodes, it's more likely to spread elsewhere.

If the sentinel lymph node contains melanoma, there is a risk that other lymph nodes in the same group will contain melanoma.

Your surgeon should discuss the pros and cons of having a sentinel lymph node biopsy before you agree to the procedure. Sentinel lymph node biopsy does not cure melanoma, but is used to investigate the outlook of your condition.

An operation to remove the remaining lymph nodes in the group may be recommended. This is known as a completion lymph node dissection or completion lymphadenectomy.

Other tests you may have include:

Want to know more?

Cancer Research UK: Melanoma tests.
Cancer Research UK: Further tests for melanoma.