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Diagnosis - Skin cancer (melanoma)

A diagnosis of melanoma usually begins with an examination of your skin.

It's important to check your moles and go to your GP if you notice any changes.

Seeing a specialist

Your GP will refer you to a specialist clinic if they think it might be melanoma.

A dermatologist (skin specialist) or plastic surgeon will examine the mole and the rest of your skin. They may remove the mole and send it to a laboratory to be tested. They usually numb the area around the mole with local anaesthetic before they remove it.

Further tests

Your doctor may do more tests to check if the melanoma has spread.

Sentinel lymph node biopsy

If the melanoma has spread, it will usually spread first to your lymph nodes. A sentinel lymph node biopsy is a test to check your lymph nodes. Your surgeon will explain the test to you and help you decide about having the test.

Your surgeon will inject a dye and a weak radioactive chemical into the area where the mole was removed (scar site).

The first lymph node the liquid reaches is the sentinel lymph node. The surgeon removes the sentinel node and sends it to a laboratory to be examined.

You will have a general anaesthetic (you are asleep) for this procedure.

You usually get your results after a few weeks. If there are no melanoma cells in the sentinel lymph node, it's unlikely that any of your lymph nodes are affected.

If the sentinel lymph node has melanoma cells, you are likely to have more tests.

Other tests

Other tests you may have include:

  • CT scan
  • MRI scan
  • PET scan
  • blood tests

Melanoma stages

Your medical team stages the melanoma. Staging means finding out how far it has grown into the skin (the thickness) and if it has spread. Your treatment depends on the stage of the melanoma.

The melanoma stages are:

Stage 0

The melanoma is on the surface of the skin.

Stage 1A

The melanoma is less than 1mm thick.

Stage 1B

The melanoma is less than 1mm thick and the surface of the skin is broken (ulcerated) or is 1mm to 2mm thick.

Stage 2A

The melanoma is 2mm to 4mm thick, or it's 1mm to 2mm thick and ulcerated.

Stage 2B

The melanoma is thicker than 4mm, or it's 2mm to 4mm thick and ulcerated.

Stage 2C

The melanoma is thicker than 4mm and ulcerated.

Stage 3

The melanoma has spread to lymph vessels or lymph nodes near where the cancer started. It is found after a sentinel lymph node biopsy or after a clinical examination in some cases.

Stage 4

The melanoma cells have spread to other parts of the body, such as the lungs, brain or other areas of the skin.

Content supplied by the NHS and adapted for Ireland by the HSE

Page last reviewed: 5 July 2023
Next review due: 5 July 2026

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.