Malignant Melanoma

A skin cancer affecting the pigment-producing cells of the skin that can spread rapidly to other parts of the body

  • Very rare in children; in adults, more common with increasing age
  • More common in females
  • Fair-skinned people are most at risk
  • Exposure to the sun and the use of sunbeds are risk factors

Malignant melanoma is an uncommon but serious form of skin cancer. A melanoma may begin as a new growth on normal skin or may develop from an existing mole. Left untreated, the cancer can spread to other parts of the body and may be fatal. The main cause of malignant melanoma is exposure to sunlight, although use of sunbeds also increases the risk of developing the cancer.

Worldwide, the number of cases of malignant melanoma, particularly in young adults, has increased significantly over the past few years, and in 2006, about 10,400 new cases were diagnosed in the UK. The incidence of malignant melanoma increases with age, and it is more common in women, although more often fatal in men.

What is the cause?

Malignant melanoma is thought to result from damage to melanocytes (the skin cells that produce the pigment melanin) by sunlight. The cancer occurs more frequently in people with fair skin than in those with dark skin. People who are continually exposed to intense sunlight or who live in sunny climates have an increased risk of developing malignant melanoma. In particular, severe sunburn during childhood has been shown to double the chance of developing malignant melanoma in later life. Minimizing exposure to the sun can help to decrease the risk of developing this type of cancer (see Safety in the sun), as can avoiding the use of sunbeds.

What are the symptoms?

Malignant melanomas can develop on any part of the body but appear most commonly on sun-exposed areas. Some melanomas spread across the skin in the form of an irregular, flat, pigmented patch; others appear as fast-growing dark lumps. Sometimes, a melanoma does not have any pigment (known as amelanotic melanoma). In older people, melanomas may occur on the face as freckle-like spots, known as lentigo maligna, that grow slowly over many years. If they are not removed, all of these types of melanoma will grow down into the underlying layers of the skin.

You should suspect a malignant mel-anoma if a quickly growing, irregular, dark-coloured spot starts to develop on your skin or if you notice any of the following changes in an existing mole:

  • Increasing size.

  • Irregular and asymmetrical edges.

  • Itching, inflammation, or redness.

  • Thickening of the surface.

  • Bleeding or crusting.

  • Variation in shade or colour.

You should check your skin regularly for any unusual changes (see Checking your skin) and consult your doctor promptly if you notice any such changes.

Malignant melanoma

The uneven colour, irregularly spreading edge, and crusted surface of this raised growth are characteristic features of a malignant melanoma.

What might be done?

If your doctor suspects that you have malignant melanoma, he or she will arrange for urgent removal of the lesion (an area of surrounding skin will also be removed to decrease the risk of malignant cells remaining). The tissue will be examined under a microscope (see Skin biopsy). If the tissue is cancerous, a larger portion of skin may be removed, which may require a skin graft. Samples may also be taken from the lymph nodes near the melanoma and examined for cancerous cells, the presence of which would indicate that the cancer has spread. If it has spread, you may have chemotherapy, radiotherapy, or biological therapies (see Cancer and its management).

What is the prognosis?

Superficial melanomas that are treated early are usually cured, but melanomas are more often fatal in men, possibly because men do not always report symptoms to the doctor immediately. If melanomas are aggressive or penetrate deep into the skin, the outlook is less optimistic, and, if they spread to other areas of the body, they are often fatal.

Can it be prevented?

You can reduce the risk of developing malignant melanoma by staying out of the sun and avoiding the use of sunbeds. In particular, you should stay out of the sun between 11am and 3pm. If you have to be out in the sun, you should wear a hat with a wide brim and tightly woven clothing that at least covers your shoulders and neck (ideally, all skin should be covered). You should protect any exposed skin with a sunscreen or sunblock. Whichever you use, you should apply it liberally 15–30 minutes before you go outside and reapply it frequently.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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