Melanoma is a form of skin cancer that develops from melanocytes, the cells responsible for producing melanin, the pigment that gives skin its colour. Although melanoma is less common than other types of skin cancer, it is more serious because it has a greater tendency to spread beyond the skin if not detected and treated early.
Melanoma is a malignant tumour that begins in melanocytes. These pigment-producing cells are found primarily in the skin but are also present in the eyes and in the lining of certain body surfaces, such as the mouth, nose and genitals. Melanoma usually develops on the skin but can arise in any area where melanocytes are present.
Melanoma often starts as a new mole or as a change in an existing mole. In some cases, it appears as a pigmented patch, a dark streak under a nail, or a lesion without obvious pigment. Because early melanoma can resemble a harmless mole, changes are sometimes overlooked.
Melanoma differs from basal cell carcinoma and squamous cell carcinoma in its behaviour. While non-melanoma skin cancers usually grow slowly and rarely spread to distant organs, melanoma has a higher risk of invading deeper layers of skin and spreading to lymph nodes or other parts of the body. This makes early detection particularly important.
Melanoma can affect people of any age, skin colour or background. It is more common in people with fair skin, light hair and light eyes, but it also occurs in people with darker skin tones. In darker skin, melanoma is more likely to develop on less sun-exposed areas such as the soles of the feet, palms of the hands or under the nails.
Melanoma most often develops on areas of skin that are exposed to the sun, including the back, legs, arms and face. However, it can also occur on areas with little or no sun exposure, such as the scalp, nails, eyes, mouth or genital skin.
Melanoma may appear as a new mole or a noticeable change in an existing mole. It can be flat or raised and may vary in colour, shape and size. Some melanomas lack pigment and appear pink, red or skin-coloured.
Healthcare professionals often use the ABCDE rule as a practical guide to help identify moles or pigmented lesions that may require further assessment. It is not a diagnostic tool on its own, but it helps highlight warning features associated with melanoma.
A – Asymmetry
One half of the mole does not match the other half in shape.
B – Border
The edges may be irregular, blurred, notched or uneven.
C – Colour
The colour is not uniform and may include different shades of brown, black, tan, red, white or blue.
D – Diameter
Melanomas are often larger than 6 millimetres, although they can be smaller when first detected.
E – Evolving
Any change in size, shape, colour, height or symptoms such as itching or bleeding is particularly important.
Among these features, evolving or changing lesions are considered especially significant. A mole that looks different from your other moles, sometimes described as the “ugly duckling” sign, should also be assessed.
It is important to remember that not all melanomas follow every ABCDE feature, and some may appear pink or skin coloured rather than dark. If a skin lesion looks unusual or changes over time, it should be examined by a GP or dermatologist.
Early review does not mean something is serious, but it allows timely diagnosis and appropriate treatment if needed.
Melanoma is often painless in its early stages. Some lesions may itch, bleed, crust or become tender. Any new symptoms affecting a mole should prompt medical review.
Melanoma develops when DNA damage in melanocytes disrupts normal cell growth. The most significant cause is exposure to ultraviolet (UV) radiation from sunlight or artificial sources such as sunbeds. UV damage may accumulate over time or result from intense sunburn.
Factors that increase risk include:
Assessment usually begins with a full skin examination by a healthcare professional. Suspicious lesions are examined closely, often using dermoscopy, which allows magnified visualisation of skin structures not visible to the naked eye.
If melanoma is suspected, the lesion is typically removed completely in an excision biopsy. This allows accurate diagnosis and assessment of tumour characteristics.
The biopsy report provides important details, including:
These features help determine the stage of melanoma and guide treatment decisions.
For higher-risk melanomas, additional tests may be recommended, such as lymph node assessment or imaging scans, to check whether the cancer has spread.
Treatment depends on the stage of melanoma, tumour thickness, and whether it has spread. Early melanoma is usually treated with surgery to remove the tumour along with a margin of surrounding healthy skin. This is often curative.
If melanoma has spread, treatment may include:
Treatment plans are tailored to the individual and managed by a specialist multidisciplinary team.
Regular follow-up appointments are important to monitor for recurrence and to detect new melanomas at an early stage.
Prognosis depends on several factors, particularly how deep the melanoma is and whether it has spread to lymph nodes or other organs. When detected early, melanoma has an excellent outlook, with high survival rates.
Melanoma can recur, and people who have had melanoma are at increased risk of developing another melanoma. Long-term monitoring and skin awareness are therefore important.
Melanoma cannot always be prevented, but steps can be taken to reduce the risk and to detect changes early. Most melanomas are linked to ultraviolet (UV) radiation, so protecting the skin from UV exposure is an important part of prevention.
Regular skin awareness is also important. Checking your skin helps you become familiar with existing moles and notice changes early. Medical advice should be sought if you notice:
Early assessment allows melanoma to be identified at an earlier stage, when treatment is more effective and outcomes are more favourable.
A comprehensive skin assessment offers clinical expertise, reassurance, and timely advice if further investigation is needed.
