Symptoms and diagnosis of melanoma

Symptoms of melanoma

The main signs may include one or more of the following:

  • A mole that suddenly gets bigger or you find a new one on your skin.
  • The mole has developed a ragged or uneven outline.
  • The mole has a mixture of different shades of brown, black or other colours through it.
  • The mole is bigger than the blunt end of a pencil.
  • The mole looks red or inflamed around the edges.
  • The mole is bleeding, oozing or crusting.
  • The mole starts to feel different, for example, slightly itchy or painful.

If you have any of the above signs, get them checked out by your doctor as soon as possible. He or she will examine you and decide what to do. Melanoma has a very good chance of being cured if diagnosed and treated early.

Remember when checking a mole, look for the ABCDE:

  • A = asymmetrical shape ( one half unlike the other)
  • B = irregular border
  • C = is for changes in colour
  • D = is for diameter (size)
  • E = is for evolving (a change over time)

Graphic showing different types of moles


Testing for cancer when you have no symptoms is called screening. There is no screening programme in Ireland for melanoma. Instead, you can examine yourself from head to toe every month. This can help you to learn the moles, freckles and other skin marks that are normal for you.

Stand in front of a long mirror to do this. Make sure you check the front, back and sides of your arms and legs. Also, check your groin, scalp and fingernails and your soles and the spaces between your toes.

If you have a risk of melanoma, talk to your doctor about getting screened more often and by a skin specialist called a dermatologist.

What is mole mapping?

Mole mapping is a check done by a specialist skin doctor called a dermatologist for people at high risk of melanoma. With mole mapping, melanoma can be diagnosed early by finding new moles or changes in moles. A dermatologist will photograph or map your moles as they are. Then, over weeks, months or years, the dermatologist will compare any changes to what he or she mapped the first time.

Mapping should be done along with a full skin examination by a doctor. Mapping a small number of suspicious moles may not be enough, and may miss moles that are hard to see.

There is no evidence to show that mole mapping is a successful means of picking up abnormalities in the general public without the addition of a full skin examination by a dermatologist. However under the direction of a dermatologist, it can help people who are at high risk. This includes people with many moles, change to their skin, or people with a family history of melanoma.

Who should consider having their moles mapped?

People who are at increased risk of the development of Melanoma should consider having their moles mapped. This includes anyone with:

  • Large number of moles (more than 50).
  • Moles that are large, or have an unusual colour or shape.
  • Previous history of melanoma.
  • A strong family history of melanoma.
  • Pale skin that burns easily in the sun.
  • Episodes of previous severe sunburn.
  • People who get a lot of sun, including outdoor workers and people who take regular sun holidays.
  • A suppressed immune system.
  • Moles on the back, which may be difficult to keep an eye on.
  • Any recent changes to individual moles.

How is mole-mapping done?

The dermatologist will:

  1. Mark spots on a cartoon drawing of you to show where any unusual marks are;
  2. Take photographs or digital images of the skin all over your body;
  3. Use a special hand-held microscope called a dermascope to look very closely at your skin;
  4. Decide if there are any signs of melanoma;
  5. Send a report to you or your GP.

The dermatologist will also follow up with you:

  • 3 to 6 months later about any unusual marks that are not removed
  • 1 to 2 years later for a check-up, or as your doctor recommends

If the dermatologist finds an unusual mark, he or she will remove it to have it examined.

The dermatologist will then decide if more tests are needed.

If you are diagnosed with melanoma our booklet has more information.


Visit your family doctor (GP) first who will examine your skin carefully. He or she can then decide to refer you to a skin specialist (dermatologist) for more tests and treatment at a hospital. Some GPs may take a sample of the affected skin and have it tested. But many GPs prefer that a skin specialist removes a suspected melanoma.

The tests at the hospital will include:

  • Skin exam: Sometimes cancer can be found by simply looking at your skin.
  • Biopsy: The only way to diagnose melanoma exactly is with a biopsy. If the mole is small, the entire mole or growth is removed, along with a small border of normal appearing skin. This is then sent to the lab for analysis.

Further tests to stage melanoma

If you are diagnosed with melanoma, the next step is to find out the extent or stage of the cancer. This is known as staging. It can help your doctor to decide on the right treatment for you.

  • Biopsy: The pathologist finds out the thickness and depth of a melanoma by looking at it under a microscope. This is known as the Breslow scale.
  • Sentinel node biopsy: In this test a tiny amount of radioactive liquid or dye is injected around the melanoma before it is removed. This radioactive liquid will show up lymph nodes that have melanoma cells. It can tell if the melanoma has spread or not.

Other tests may include:

  • CT scan
  • Ultrasound scan of liver and abdomen
  • Bone scan
  • MRI scan

See Understanding Melanoma Booklet for more information on tests.

Learn more about the above tests

What are the stages of melanoma?

Staging means finding out the size of the tumour and if it has spread to other parts of your body.

Staging is very important as it allows your doctor to decide the best treatment for you.

There are different ways to stage melanoma. A common method is the Breslow scale. This scale refers to the thickness of the tumour within your skin. The thickness (depth) is measured in the laboratory once the tumour is removed. It can find out if the cancer cells have spread into the deeper layers of your skin.

Read next: Treatment for melanoma.

Date Last Reviewed: 
Monday, November 5, 2018