Melanoma

What is melanoma?

Melanoma is a skin cancer arising from melanocytes, the pigment-making cells of the skin. Although rarer than the other two main skin cancers, basal cell and squamous cell carcinoma, melanoma is the most dangerous, as it is more prone to spreading through the body. Around 18,300 people are diagnosed with melanoma in the UK each year, making it the fifth most common cancer, and rates have risen over recent decades.

When melanoma is picked up early, while still thin and limited to the skin, the outlook is excellent. This is why early detection is so important.

Who gets it?

Melanoma can affect anyone, including young adults. In younger adults women are affected more, whereas in later life men are affected more.

The risk is higher in people with fair skin that burns easily, freckles, red or fair hair and light-coloured eyes; a large number of moles (over 100) or atypical moles; a very large mole present from birth (giant congenital naevus); severe, blistering sunburn, particularly in childhood; use of sunbeds; a family history of melanoma; a previous melanoma; and a weakened immune system.

What causes it?

The main cause is damage to the DNA of melanocytes from ultraviolet (UV) light, from the sun or from artificial sources such as sunbeds. About 85 in 100 melanomas in the UK are thought to be caused by too much UV exposure. Some melanomas, particularly those on the palms, soles and nails, are less clearly related to sun exposure. Inherited factors also play a part, including an inherited tendency to have many or atypical moles.

Is it hereditary or contagious?

Most melanomas are not inherited, but a family history of melanoma increases the risk, and a small number of families carry genes that greatly increase it. People with a strong family history, such as three or more affected relatives, may be offered genetic counselling. Melanoma is not contagious.

What does it look and feel like?

Most melanomas appear as a new mark on the skin, but some develop from an existing mole. Early signs include a mole that changes colour or darkens, or a new brown or black spot. It can occur anywhere on the body. In men it most often appears on the trunk, particularly the back, and in women on the legs, but it can also appear on the scalp, face, palms, soles, under the nails, and on the genitals or inside the mouth. In people with brown and black skin, melanoma is less common overall but is more often found on the hands, feet and nails.

The ABCDE guide can help you recognise warning signs. Asymmetry: the two halves of the mark look different. Border: the edge is irregular, ragged or blurred. Colour: the colour is patchy, or a mix of shades is present, for example brown, black, blue, grey, pink, red or white. Diameter: it is larger than about 6 mm, although melanomas can be smaller. Evolving: it is changing in size, shape, colour or height, or developing new symptoms such as itching, crusting or bleeding.

Not all melanomas follow these rules. Some lose pigment and develop pale or red areas, and some have little or no pigment at all, appearing pink or red (amelanotic melanoma). Nodular melanoma can grow quickly as a firm, raised lump. Lentigo maligna is a brown patch that has been present for some time and gradually grows, usually on the face of an older person, and may darken in places as time passes. A dark streak in a nail that is new or changing should also be checked.

How is it diagnosed?

A suspicious mark is examined by a dermatologist or plastic surgeon, usually with a dermatoscope. When melanoma is suspected, the entire mark is cut out under local anaesthetic, together with a small rim of healthy skin, and a pathologist then examines it under the microscope. The pathology report confirms the diagnosis and describes two key features used for staging: the Breslow thickness, which is how deeply the melanoma cells have grown into the skin, measured in millimetres, and whether there is ulceration, meaning a breakdown of the skin surface seen under the microscope.

Stages of melanoma

Doctors stage melanoma with the AJCC system, devised by the American Joint Committee on Cancer. This looks at how thick the melanoma is, whether its surface is ulcerated, and whether it has spread.

Melanoma in situ (stage 0) is the earliest stage. Here the melanoma cells sit only within the epidermis, the outermost layer of skin, without having invaded deeper or spread. Lentigo maligna is one type of melanoma in situ.

A stage 1A melanoma measures under 0.8 mm in thickness, with no ulceration. It is confined to the skin, with no spread to the lymph glands or elsewhere.

Stage 1B melanoma is either between 0.8 mm and 2 mm thick without ulceration, or less than 0.8 mm thick with ulceration. It is also confined to the skin.

Stage 2 melanoma is still confined to the skin but is thicker and may be ulcerated. Depending on the Breslow thickness and the presence or absence of ulceration, it is split into stages 2A, 2B and 2C.

Stage 3 melanoma has spread towards or into the nearest lymph glands (nodes). This may be found as an enlarged gland that can be felt, often around the size of an olive; as microscopic spread found on a sentinel lymph node biopsy when the glands feel normal; or as small deposits of melanoma in the skin around the original melanoma, known as satellite or in-transit deposits, which lie between the melanoma and the nearest lymph glands. Stage 3 is divided into stages 3A, 3B, 3C and 3D.

In stage 4, melanoma has travelled past the nearby lymph glands to more distant sites. These can include skin or lymph glands further away, or organs such as the lungs, liver, brain and bones. Stage 4 melanoma may cause no symptoms when it is found on a scan, or it can cause a wide range of symptoms depending on which parts of the body are affected.

Staging tests

For stage 1B and stage 2 melanoma, a sentinel lymph node biopsy may be offered as an optional staging test. A scan with a small amount of radioactive tracer, and sometimes a blue dye, is used to find the first lymph gland that drains the area of the melanoma (the sentinel node). This gland is removed and examined under the microscope, with results usually available in around four weeks. If melanoma cells are found, the melanoma is reclassified as stage 3. A clear result makes a return of the melanoma much less likely, although it cannot rule it out completely.

For stage 3 and stage 4 melanoma, further tests may include needle biopsies, blood tests and scans such as ultrasound, CT, MRI, PET and bone scans to see how far the melanoma has spread. Samples of the melanoma are also tested for a genetic change called a BRAF mutation, which is found in about half of melanomas and helps guide decisions about treatment. Results are discussed by a specialist multidisciplinary team.

What are the treatment options?

Dr Mounsey will examine any suspicious mole with a dermatoscope and, if melanoma is suspected, remove it completely by excision for diagnosis. If melanoma is confirmed, a further wider excision is usually needed, and your case will be discussed by a specialist skin cancer team. Depending on the stage, this may include a sentinel lymph node biopsy, scans, and treatments such as immunotherapy or targeted therapy, which are given by oncology colleagues. Dr Mounsey will coordinate your care, arrange referrals and provide long-term skin checks, including mole mapping where helpful.

What is the outlook?

The outlook depends mainly on the stage at diagnosis. Melanoma in situ has an excellent outlook: once completely removed, it rarely comes back, and life expectancy is normal. Most people with stage 1 and stage 2 melanoma do not have a recurrence once it has been treated. Although the chance of stage 3 melanoma returning is greater, and it needs to be taken seriously, it can still be cured. The outlook for stage 4 melanoma varies widely from person to person, and treatment for advanced melanoma has changed considerably in recent years.

Anyone who has had a melanoma has a higher risk of developing another, so regular self-examination of the skin, prompt assessment of any new or changing mark, and careful sun protection are important.

Follow-up

After a diagnosis of melanoma, regular follow-up is arranged to check for any signs of the melanoma coming back and to look for new melanomas. For stage 1B to stage 3 melanoma, follow-up typically takes place every three to six months for five years, often every three months for the first three years and then every six months until five years.

More information

British Association of Dermatologists patient leaflet on melanoma in situ: https://www.bad.org.uk/pils/melanoma-in-situ

British Association of Dermatologists patient leaflet on stage 1A melanoma: https://www.bad.org.uk/pils/melanoma-stage-1a

British Association of Dermatologists patient leaflet on stage 1B melanoma: https://www.bad.org.uk/pils/melanoma-stage-1b

British Association of Dermatologists patient leaflet on stage 2 melanoma: https://www.bad.org.uk/pils/melanoma-stage-2

British Association of Dermatologists patient leaflet on stage 3 melanoma: https://www.bad.org.uk/pils/melanoma-stage-3

British Association of Dermatologists patient leaflet on stage 4 melanoma: https://www.bad.org.uk/pils/melanoma-stage-4

British Association of Dermatologists patient leaflet on lentigo maligna: https://www.bad.org.uk/pils/lentigo-maligna

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.