Melanoma

What is melanoma?

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the main causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanocytes make a brown/black pigment (known as melanin), and often the first sign of a melanoma developing is a previous mole changing in colour or a new brown/black spot developing on the skin. Most frequently there is darkening in colour but occasionally there is loss of pigmentation with pale areas or red areas developing. Occasionally melanomas have no pigment and appear just a pink/red colour. The development of this melanoma on the skin is known as the primary melanoma.

Melanoma is considered to be the most serious type of skin cancer. This is because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases). Although a diagnosis of melanoma can be serious, most melanomas are diagnosed at an early stage and so do not cause any further problems. If lesions are not removed at the early stages, then there is a higher risk of the melanoma spreading, which can reduce life expectancy.

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What causes melanoma?

The most important preventable cause is exposure to too much ultraviolet light in sunlight, especially during the first 20 years of life. There is lots of evidence linking melanoma to this, and melanomas are especially common in white-skinned people who live in sunny countries. The use of artificial sources of ultraviolet light, such as sun beds, also raises the risk of getting a melanoma.

Some people are more likely to get a melanoma than others:

People who burn easily in the sun are particularly at risk. Melanoma occurs most often in fair-skinned people who tan poorly. Often they have blond or red hair, blue or green eyes, and freckle easily. Melanomas are less common in dark-skinned people.
Past episodes of severe sunburn, often with blisters, and particularly in childhood, increase the risk of developing a melanoma. However, not all melanomas are due to sun exposure, and some appear in areas that are normally kept covered.
People with many (more than 50) ordinary moles, or with a very large dark hairy birthmark, have a higher than average chance of getting a melanoma.
Some people have many unusual (atypical) moles (known as ‘dysplastic naevi’). They tend to be larger than ordinary moles, to be present in large numbers, and to have irregular edges or colour patterns. The tendency to have these ‘dysplastic naevi’ can run in families and carries an increased risk of getting a melanoma.
The risk is raised if another family member has had a melanoma.
People who have already had one melanoma are at an increased risk of getting another one.
People with a damaged immune system (e.g. as a result of an HIV infection or taking immunosuppressive drugs, perhaps after an organ transplant) have an increased chance of getting a melanoma.

Is melanoma hereditary?

About 1 in 10 of people with a melanoma have family members who have also had one. There are several reasons for this. Fair skin is inherited; dysplastic naevi can run in families, as can a tendency to have large numbers of ordinary moles.

What are the symptoms of melanoma?

Melanomas may not cause any symptoms at all, but tingling or itching may occur at an early stage. Some melanomas start as minor changes in the size, shape or colour of an existing mole (see below): others begin as a dark area that can look like a new mole. Later on a melanoma may feel hard and lumpy, and bleed, ooze or crust up.

What does a melanoma look like?

All melanomas do not look the same, and there are several different types. The ABCD system (below) tells you some of the things to look out for.

A melanoma may show one or more of the following features:

Asymmetry – the two halves of the area differ in their shape.

Border – the edges of the area may be irregular or blurred, and sometimes show notches.

Colour – this may be uneven. Different shades of black, brown and pink may be seen.

Diameter – most melanomas are at least 6 mm. in diameter.

Melanomas can appear on any part of the skin but they are most common in men on the body, and in women on the legs.

How is a melanoma diagnosed?

The clinical diagnosis of melanoma is usually made by a specialist (normally a dermatologist or plastic surgeon) by looking at the skin. The initial treatment for a suspected melanoma is to cut out (excise) all of the melanoma cells. Usually this is a minor operation done under a local anaesthetic (via an injection to numb the skin). When the lesion is first removed, although your specialist may feel that it is likely to be a melanoma, the diagnosis needs to be confirmed by examining the tissue removed under a microscope, so the excision is usually done with narrow margins (a thin rim of normal skin around the suspected melanoma). The specimen that is cut out from the skin is sent to a laboratory, so that a pathologist can examine it under the microscope and then confirm if it is a melanoma or not.

Can a melanoma be cured?

Yes: three quarters of the people who have a melanoma removed will have no further problems. However it is crucial for a melanoma to be removed as early as possible – before it has had time to spread deep into the skin or to other parts of the body. The thinner the melanoma is when it is removed; the better is the survival rate. This is why a doctor should examine anyone with a suspicious mole or blemish as soon as possible. In a small minority of people the melanoma may have spread but further surgery or chemotherapy can often help to control this.