Skin cancer: Malignant melanoma

• What is skin melanoma?
• Statistics on melanoma
• Risk factors for melanoma
• Progression of melanoma
• Prevention of melanoma
• Symptoms of melanoma
• Clinical examination of melanoma
• How is melanoma diagnosed?
• How is melanoma treated?
• References

What is melanoma?

Melanoma is a type of skin cancer that originates from the cells in the skin responsible for pigmentation (colour), known as melanocytes. Melanoma can occur in adults or children and in rarer cases can even be present at birth (congenital melanoma). Typically, melanomas occur on areas of the skin that have been overexposed to sunlight. However, melanoma can also occur in areas of the skin that have not been exposed to sunlight and it may even, although less common, occur in areas such as the nervous system, eye, linings of the nose, mouth and anus as well as the genital tract (urethra and vagina).

This article focuses on melanomas affecting the skin. Melanomas affecting the skin can be divided into four different types based on how they look, how thick they are and how they spread.

Superficial spreading melanoma

This is the most common type of melanoma (~65% of all cases). This type typically starts as a brown or black spot that spreads across the skin and can also invade the structures lying beneath. It may present as a new spot or it may develop from an existing spot, freckle or mole that changes in either size, colour or shape.

Nodular melanoma

Nodular melanoma is seen in approximately 15% of all melanomas. This is a highly aggressive melanoma that grows quickly. Typically it presents as a raised lump that may be either very dark brownish-black, black, pink, red or have no colour at all. It is often firm to touch and is more likely to have uniform colour (one colour rather that different colours or shades of colour) and be symmetrical in shape compared to other melanomas. It may become crusty and/or bleed easily. This particular type invades the deeper structures quickly such that it can become life threatening in as little as 6-8 weeks. This particular form is often found on the head and neck areas and commonly found in those of an older age, especially males.

Lentigo maligna melanoma

Representing approximately 10% of melanomas, this type is most commonly found in the elderly population. It often begins as a large freckle in an area of skin exposed to the sun such as the face, ears, neck and head. These melanomas typically grow slowly for many years prior to invading deeper structures.

Acral lentiginous melanoma

This particular type of melanoma is very rare. They are most commonly found under the nails or on the palms and soles of the hands and feet respectively.

Statistics on melanoma

In Australia we have some of the highest rates of skin cancer in the world. It is estimated that two out of every three Australians will develop a skin cancer before the age of 70.

While melanoma is less common than other forms of skin cancer, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), it is estimated that one in fourteen Australian males and one in twenty three Australian females will develop melanoma in their lifetime. For those aged 15-39, melanoma is the most common cancer in males and the second most common cancer in females.

Melanoma represents the fourth most common cancer (excluding non-melanoma skin cancer) in Australia behind prostate, colorectal and breast cancer. The incidence of melanoma in non-Caucasians is low, however, when melanoma is diagnosed in these individuals, the diagnosis is often delayed and as a result the prognosis is often poorer.

Up to 4% of all cases of melanoma occur in children (up to the age of 21). Between 1 and 3% of all cancers diagnosed in children will be melanoma.

Risk factors for melanoma

There are a number of risk factors for developing melanoma that have been identified, these include:

• Multiple naevi (moles);
• Personal or family history of melanoma (i.e. either yourself or a family member have been diagnosed with melanoma previously);
• Increasing age;
• Sun exposure;
• Personal history of other skin cancers such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC);
• Having fair skin that easily burns, freckles and doesn’t tan;
• Characteristics such as fair or red coloured hair and either blue or green eyes; and
• Those who are immunosuppressed or have received an organ transplant.

The main lifestyle risk factor for developing skin cancer, including melanoma, is unprotected exposure to ultraviolet radiation (e.g. sun exposure or Solaria use). The pattern of sun exposure is highly important. For melanoma, the highest risk comes from an intermittent pattern of sun exposure (e.g. recreational where you are exposed on weekends but not weekdays) rather than a continuous pattern (e.g. occupational where you may be exposed on a daily basis). Childhood sun exposure gives a higher risk of melanoma compared to sun exposure later in life.

Learn more about skin colour, skin types and sun exposure and cancer risk. Visit Skin Colour.

Progression of melanoma

The first step in the development of melanoma involves the transformation of melanocytes (the cells in the skin responsible for pigmentation – colour) into cancerous cells. The risk of this occurring depends on a number of risk factors identified above (see Risk Factors).

These cancerous cells can then replicate to create more cancerous cells. As the cells replicate and increase in number they can then spread across the skin (such that the lesion increases in diameter) and/or invade the structures underlying the skin. Depending on the type of melanoma some melanomas will grow across the skin before invading deeper structures whilst others will grow relatively little across the skin but will invade the deeper structures rapidly (nodular melanoma).

Once the melanoma cells invade the deeper structures they can spread via the body’s circulation to other distant sites within the body. When spread to distant sites occur, this is called as metastasis. When this occurs, a diagnosis of metastatic melanoma is given.

To learn more about staging and progression of melanoma, visit Staging of Skin (Cutaneous) Melanoma.

Prevention of melanoma

Prevention of melanoma is based upon minimisation of modifiable risk factors. Strategies include:

• Minimise sun exposure when the SunSmart UV Alert exceeds 3 and especially in the middle of the day when UV levels are most intense
• Avoid sunburn
• Seek shade
• Wear a hat that covers the head, neck and ears
• Wear sun protective clothing
• Wear close-fitting sunglasses
• Wear an SPF 30+ sunscreen
• Avoid the use of solariums (taning salons)

For more information on the different things you can do to prevent skin cancer, read Skin Cancer Prevention.

Symptoms of melanoma

The symptoms of melanoma can vary widely between individuals.

Some individuals may not have any symptoms at all, others may have symptoms related to the primary melanoma (the site where the melanoma first developed) and others may have symptoms related to sites that melanoma has spread to.

Symptoms related to the primary melanoma

You may notice a new skin spot or you may notice changes in a skin spot that has been there before. You may notice a change in its appearance i.e. that the spot increases in size, forms a nodule and/or changes colour. These may itch, which can give rise to bleeding and ulceration. If you notice any of these changes or have concern about any skin spot, you should seek medical advice from your General Practitioner or Dermatologist (doctor who specialises in the skin).

Note that melanoma in children can appear quite different to those in the adult population. The most common signs and symptoms of melanoma in children are increasing size, bleeding, change in colour, itching, and your doctor may be able to feel a mass under the skin.

Symptoms related to melanoma spread elsewhere (metastasis)

Depending on where the primary melanoma is (the site where the melanoma first developed) and your medical history you may not necessarily have symptoms relating to the primary melanoma. For some people the first symptoms that they have are related to the spread of the melanoma to elsewhere. This can include, but is not limited to:

• pain – related to where the melanoma has spread to e.g. bone pain
• liver problems – which may be picked up incidentally on routine blood tests or you may become jaundiced (the whites of your eyes turn yellow) or may have problems stopping bleeding
• weight loss – the growing cancer cells can increase your metabolic demands and use increased amounts of energy and hence any unintentional weight loss should be mentioned to your General Practitioner
• altered behaviour and/or seizures – if the cancer cells have spread to the brain

Clinical examination of melanoma

When you see you Doctor for a concerning skin lesion, they are likely to perform a skin check. This involves taking a detailed look at the skin surfaces for any lesions of concern. The things that they will be looking for to distinguish a melanoma from a mole include:

1. Asymmetry:
   they will note the shape and/or pattern of the lesion. A lesion that has an irregular shape or pattern is more likely to be a melanoma.
2. Border:
   they will note the border of the lesion. The border or outline of a melanoma is usually irregular.
3. Colour:
   Variation of colour within the lesion is an important sign as such lesions are more likely to be a melanoma.
4. Diameter:
   Most melanomas are greater than 6mm when first diagnosed. However, any lesions less than 6mm of diameter that are suspicious should also be investigated.
5. Evolving:
   Lesions that evolve (i.e. change in shape, size, surface, colour or symptoms such as itch) over time are more likely to be a melanoma.

However, one particular type of melanoma – nodular melanoma – can present quite differently and hence your doctor will also be looking for skin lesions that are elevated and firm to touch. Any nodule that has been growing for more than a month should be assessed as a matter of urgency.

Your doctor may or may not use photography or a special viewing instrument (dermatoscope).

Dr. Dean explains the different ways to have your skin checked for melanoma in this useful video: Melanoma Prevention and Skin Checks.

How is melanoma diagnosed?

If your doctor has concern about a lesion they may discuss the option of performing a skin biopsy. This involves removing the lesion (less commonly part of the lesion) and sending it for histopathology (where the specimen is looked at under a microscope to determine the cells present) to determine if the lesion is a melanoma, a different type of skin cancer, normal or a different diagnosis altogether.

Depending on what the skin biopsy shows it may be necessary to perform other investigations to determine if there has been any spread to other parts of the body. This will be discussed in detail with you by your General Practitioner or Specialist.

For more information on the different types of skin biopsies, including how to care for the wound after the procedure, visit Skin Biopsy.

How is melanoma treated?

The treatments for melanoma vary depending on how advanced the melanoma is. Generally when melanoma is diagnosed, it is given a stage – this is a method of classifying melanomas into groups – to aid communications, give indications on prognosis and direct appropriate treatment options.

For more information on the different Melanoma treatments available, watch Dr. Dean’s video Treatment for Melanoma.

Excision (removal) is the standard treatment for primary melanoma (the site where the melanoma originated from). If the cancerous cells have spread to the lymph nodes (part of the immune system) it may be an option to have these removed surgically. For those individuals with more advanced disease i.e. the cancerous cells have spread to one or more distant sites (metastasis) options such as adjuvant systemic therapy, chemotherapy, radiotherapy and/or resection of single or multiple metastasis may be offered. Each of these are discussed in more detail below. Psychological support also plays an important role in the treatment of those diagnosed with melanoma.

Excision

Wide local excision of the skin and tissue that underlies the skin (subcutaneous tissue) is the standard treatment for primary melanoma. How wide (or how big) the excision is depends on how thick the melanoma is.

The aim of this approach is to completely remove the melanoma and this should be confirmed by sending the removed tissue to histopathology – where the samples are sent and looked at under a microscope to determine which cells are present. Ideally the excised tissue includes a rim of normal cells that surrounds the melanoma.

Depending on where the melanoma is located and how extensive the excision is you may or may not have to stay in overnight or longer in hospital. Some of the complications that can occur include:

• Wound infection – where the wound becomes infected and antibiotics may be required
• Haematoma – a collection of blood at the wound site that may impair wound healing
• Numbness – depending on the location, nerve damage may occur giving rise to numbness
• Scarring – a scar may develop
• Further surgery – may be required if not all of the cancer was able to be removed, this can be confirmed with histopathology

Depending on the stage of your melanoma you may or may not be given treatment with medications in addition to removing the cancer surgically. This is known as adjuvant therapy as it is given in addition to surgical removal.

Therapeutic lymph node dissection

Therapeutic lymph node dissection in simple terms means the removal of a group of lymph nodes. This is done surgically in an operating theatre under a general anaesthetic. Lymph nodes are collections of immune cells that form part of the lymphatic system (part of the circulation which is important for the return of fluids to the blood supply) and are often the first place that the cancerous cells spread to. As the lymph nodes have such an important function and roughly 1/3 of people undergoing the procedure will suffer complications, this procedure can only be offered to a select group of individuals.

Topical creams

Imiquimod (Aldara) is a medication that when applied to the skin as a cream stimulates the local immune response. Its use is limited, some doctors may use it for very early melanomas on very sensitive areas such as the face where surgery can be disfiguring. However, there is debate amongst doctors whether it should be used for melanoma. It is not suitable for more advanced melanomas and may cause serious skin reactions.

Treatment of metastatic melanoma

In those with metastatic melanoma there are a number of treatment options available.

Chemotherapy

This may be offered, however, the response may be poor and last only for a short duration.

Radiotherapy

This can help improve the symptoms related to the presence of tumours in the bone, brain, soft tissues and some organs. The main use of radiotherapy is in the palliative care setting in order to improve quality of life e.g. to reduce pain etc

Surgery

This may be offered where there is a limited number of metastases (spread to distant sites) and these are at sites that are accessible by surgery.

Immunotherapy

This makes use of medicines which stimulate a patient’s own immune system so that their immune system can more effectively recognise and destroy cancer cells. The use of such agents can have serious side effects and hence it is important that these are only administered by an Oncologist (cancer specialist) with experience the area.

For more information on Immunotherapy, visit Immunotherapy for Cutaneous Melanoma.

BRAF inhibitors

Some melanomas have a genetic mutation that makes them sensitive to a group of medications called BRAF inhibitors. These agents have been shown to cause melanomas to regress and may also improve your immune system’s ability to recognize and destroy the cancerous cells. However, some people may develop resistance to these medications and hence relapse. They are only available to those people with melanomas that have the genetic mutation and the benefits must be weighed against the side effects. This will require discussion with your Oncologist (cancer specialist).

Complementary and alternative medicine

Complementary and alternative medicine (CAM) is a term used to group medical products and practices that are not part of standard medical care. Where these are used in addition to standard treatments, they are referred to as ‘complementary’; where these are used instead of standard treatments they are referred to as ‘alternative’. Providers of such treatments may claim that their products and/or practices have promising benefits, however, often we do not know how safe or how effective they are.

The National Cancer Institute have developed some tools and guides to help people with cancer make informed choices when looking for complementary and alternative medicines as well as for health care providers to talk about the use of CAM during and after cancer care which can be found here: Complementary and Alternative Medicine (CAM) .

Psychological aspects

A diagnosis of melanoma can be psychologically challenging for the patients, their families and carers. Challenges vary from individual to individual, however, some common issues include having a diagnosis of a life threatening disease, the pain and discomfort associated with treatment, changes in body image secondary to disfiguring surgery, the fears of relapse and the sadness of late stage disease. Structured psychosocial interventions are available and include cognitive behavioural therapy, group therapy, psycho-education and support groups.

Follow-up

The main purpose of follow up is to detect progression or recurrences early. The assumption is that earlier treatment may result in improved disease control, improved quality of life and improved survival. It is likely that most people will detect their own recurrence (rather than being told by a doctor) and in Australia this may be the case in up to 75% of people. The frequency of follow-up with your Oncologist (cancer specialist) can vary between every 3-6 months over a five year period.

Kindly written and reviewed by Dr Allison Johns Bsc (Hons) MBBS, Doctor at Child and Adolescent Health Services and Editorial Advisory Board Member of Virtual Medical Centre.

To learn more about Melanoma, including symptoms, types, prevention strategies and treatments, visit  Melanoma.

References

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