Melanoma

Melanoma is a type of cancer that occurs in your skin. It often appears as a new spot on normal skin or develops from an existing mole.

Key points

  1. Melanoma is the most dangerous type of skin cancer. If left untreated, it can spread rapidly to other parts of your body and become life-threatening.
  2. New Zealand has one of the highest rates of melanoma in the world.
  3. It’s important to have regular skin checks by your doctor and if you notice any darker, growing or changing moles, to get them checked straight away. 
  4. If melanoma is recognised and treated early enough, it is almost always curable.

What is melanoma?  

Melanoma is a type of cancer that begins in your skin's pigment cells, known as melanocytes.

Melanocytes produce a brown-coloured pigment called melanin. This gives skin its colour. When melanocyte cells group together in the skin they can form a mole.

Most moles are safe. However, sometimes the melanocytes in them begin to grow and divide in an uncontrolled way and form a melanoma.

Melanoma is the most serious type of skin cancer and it can spread quickly. It is treatable if it is caught early, but if the cancer spreads to other parts of your body, it can be life-threatening.

What causes melanoma?

Most melanomas are caused by overexposure to sunlight, or more specifically UV radiation. Each time your unprotected skin is exposed to UV radiation from the sun or other sources, such as sunbeds, the UV radiation causes changes to the structure of the melanocytes. 

This causes your skin to become permanently damaged. The damage worsens with more UV radiation.

Where do melanomas occur?

Melanoma occurs most commonly on parts of your body that have been sunburned. However, it can appear in skin anywhere on your body – even on parts that aren’t usually exposed to the sun, such as the soles of your feet or under your toenails.

What do melanomas look like?

Melanoma can:

  • appear as a new spot
  • be an existing spot, freckle or mole that changes colour, size or shape
  • sometimes be itchy or bleed
  • look different to other spots
  • be raised (sticking out) and look shiny
  • appear quickly.

See DermNet New Zealand for images of melanoma

What should I do if I think I have a melanoma?

If you are worried that you have a melanoma, see your doctor or a qualified skin check provider for an examination. If they think the mole or lesion is suspicious, they will take a small sample, known as a biopsy. 

A biopsy is a simple procedure in which a part or all of the lesion is surgically removed and sent to the lab for testing. This can be done at your doctors or you might be referred to a dermatologist or surgeon.

The results will be sent back to your doctor, who will let you know if melanoma or another type of skin cancer was found. If the mole or lesion was found to be melanoma, your doctor will discuss with you what stage (how advanced) it is and the treatment required. 

Stages

  • Stage 0 – (melanoma in situ) abnormal cells found in the epidermis (outer layer of your skin). 
  • Stage 1 – the melanoma is not more than 2mm thick.
  • Stage 2 – the melanoma is more than 2 to 4mm thick with no spread to your lymph vessels or lymph nodes.
  • Stage 3 – any thickness of melanoma that has spread to your lymph vessels or lymph nodes.
  • Stage 4 – the melanoma has spread to other parts of your body. 

If a melanoma is caught early, it can normally be treated successfully. If it has spread to other parts of your body, it can be harder to treat.

Read more about treatment of skin cancer

How can melanoma be prevented?

Do the following to reduce your risk of getting a melanoma:

  • Protect your skin from the sun.
  • Do not use sunbeds or sunlamps.
  • Get your skin checked by your doctor and do regular self-checks. See skin self-checks

Ways to protect your skin

  • Avoid outdoor activities when the sun is strongest – between 10 am and 4 pm during September to April in New Zealand.
  • Wear sunscreen and lip balm daily that offer SPF 30 or higher sun protection.
  • Use sunscreen that offers broad-spectrum (UVA/UVB) protection and is water resistant. 
  • Apply the sunscreen and lip balm to dry skin 15 minutes before going outdoors. 
  • Apply the sunscreen to every part of your body that will not be covered by clothing. Reapply it every two hours if you are swimming or sweating.
  • Whenever possible, wear a wide-brimmed hat, long sleeves and long pants. 
  • Wear sunglasses to protect the skin around your eyes. 
  • Avoid getting a tan and never use a tanning bed or sun lamp. 

See also skin cancer prevention and sun safety

Learn more

Credits: Health Navigator Editorial Team. Last reviewed: 06 Dec 2017