Melanoma is a type of skin cancer that can spread to other organs in the body.

The most common sign of melanoma is the appearance of a new mole or a change in an existing mole. This can happen anywhere on the body, but the back, legs, arms and face are most commonly affected.

In most cases, melanomas have an irregular shape and more than one colour. They may also be larger than normal moles and can sometimes be itchy or bleed.


Symptoms of melanoma 

The first sign of a melanoma is often a new mole or a change in the appearance of an existing mole.

Normal moles are usually round or oval, with a smooth edge, and no bigger than 6mm (1/4 inch) in diameter.

See your GP as soon as possible if you notice changes in a mole, freckle or patch of skin, especially if the changes happen over a few weeks or months.

Signs to look out for include a mole that is:

  • getting bigger

  • changing shape

  • changing colour

  • bleeding or becoming crusty

  • itchy or painful

A helpful way to tell the difference between a normal mole and a melanoma is the ABCDE checklist:

  • Asymmetrical – melanomas have two very different halves and are an irregular shape.

  • Border – melanomas have a notched or ragged border.

  • Colours – melanomas will be a mix of two or more colours.

  • Diameter – melanomas are larger than 6mm (1/4 inch) in diameter.

  • Enlargement or elevation – a mole that changes size over time is more likely to be a melanoma.

Causes of melanoma

Sunlight. Most skin cancer is caused by ultraviolet (UV) light damaging the DNA in skin cells. The main source of UV light is sunlight.

Artificial sources of light, such as sunlamps and tanning beds, also increase your risk of developing skin cancer.

Repeated sunburn, either by the sun or artificial sources of light, increases the risk of melanoma in people of all ages.

Moles. You are at an increased risk of melanoma if you have lots of moles on your body, especially if they are large (over 5mm) or unusually shaped.

Having just one unusually shaped or very large mole increases your risk of melanoma by 60%.

For this reason, it’s important to monitor moles for changes and avoid exposing them to the sun.

Family history. Research suggests that if you have two or more close relatives who have had non-melanoma skin cancer, your chances of developing the condition may be increased.

Increased risk

Certain things are believed to increase your chances of developing all types of skin cancer, including:

  • pale skin that does not tan easily

  • red or blonde hair

  • blue eyes

  • older age

  • a large number of freckles

  • an area of skin previously damaged by burning or radiotherapy treatment

  • a condition that suppresses your immune system – such as HIV

    medicines that suppress your immune system (immunosuppressants) – commonly used after organ transplants

  • exposure to certain chemicals – such as creosote and arsenic

  • a previous diagnosis of skin cancer

Diagnosing melanoma

A diagnosis of melanoma will usually begin with an examination of your skin. Your GP will refer you to a specialist (dermatologist or plastic surgeon )if they suspect melanoma. 

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 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

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.

(CT) scan, a computerised tomography

(MRI) scan, a magnetic resonance imaging

(PET) scan, a positron emission tomography

Blood tests

Treating melanoma

Surgery is the main treatment for melanoma, although it often depends on your individual circumstances.

People with melanoma skin cancer should be cared for by a team of specialists that often includes a dermatologist, a plastic surgeon, an oncologist (a radiotherapy and chemotherapy specialist), a pathologist and a specialist nurse.

When helping you decide on your treatment, the team will consider:

  • the type of cancer you have

  • the stage of your cancer (how big it is and how far it has spread)

  • your general health

Your team will recommend what they believe to be the best treatment option.

Before going to hospital to discuss your treatment options, you may find it useful to write a list of questions to ask the specialist. For example, you may want to find out what the advantages and disadvantages of particular treatments are.