Melanomas are a type of cancer that develop from melanocytes, which are the cells that produce pigment, generally in the skin. However, they can also develop in the eye and possibly other parts of the body. Cutaneous melanoma refers to melanomas of the skin, and is one of the most common types of skin cancer.
The skin is the largest organ in our bodies that protect us from injury, loss of bodily fluids and help regulate body temperature. There are three layers of the skin: epidermis (top layer), dermis (middle layer) and hypodermis (bottom layer). The epidermis is the water-resistant outer layer of the skin that acts as the body’s first line of defence. It contains squamous cells (upper layer of the epidermis), basal cells (lower layer of epidermis) and melanocytes. The dermis contains the skin’s connective tissues, as well as hair follicles, sweat glands, blood vessels, lymph nodes and nerves. The hypodermis, also known as subcutaneous tissue layer, stores fat (adipose cells), and also contains connective tissue, blood vessels and nerve cells.
Melanoma is most common in males; however, anyone can develop this disease at any age.
Types of Cutaneous Melanoma
There are several types of cutaneous melanoma, which are classified by the by their appearance on the skin.
Superficial Spreading Melanoma
Superficial spreading melanoma is the most common type of melanoma, and is generally found in people under 40. This type of cancer often appears as a new black or brown spot on the skin, or as a spot, freckle or mole that changes in appearance (e.g., size, shape, colour etc.). These cancers can appear anywhere on the body, but is most commonly found on the trunk of the body. Superficial spreading melanomas are often slow growing, but can become aggressive when it grows into the dermis layer of the skin.
Nodular Melanoma
Nodular melanoma is a less common subtype of melanoma that generally affects people over 65. These melanomas often appear as pink, red, brown or black lumps (or nodules) on the skin. Nodular melanomas are usually found on skin that has been damaged by the sun, especially on the head and neck, and can be aggressive.
Lentigo Malinga Melanoma
Lentigo Malinga melanomas are a less common subtype of melanoma that mainly affects people over 40. It often occurs as a large, coloured spot on the skin (letting Malinga) on sun-damaged skin, usually on the face, ears, and neck. This subtype is often very slow growing, and may progress over many years before spreading into the dermis layer of the skin.
Acral Lentiginous Melanoma
Acral lentiginous melanomas are a rare form of melanoma that generally affects people over 40. They are often light in colour or colourless, so they may be mistaken for a bruise or a skin stain. Acral lentiginous melanomas are commonly found in the palms of your hands, the soles of your feet or under your finger/toenails. This subtype of melanoma is often slow growing, but may become aggressive when it grows into the dermis layer of the skin.
Desmoplastic Melanoma
Desmoplastic melanomas are a rare subtype of melanoma that generally affects people over 60. This type of cancer often appears as a colourless, firm, lump on the skin, and can be difficult to diagnose. They are mainly found on sun-damaged skin, particularly on the head and neck. Desmoplastic melanomas are the slowest growing subtype of melanoma; however, it is usually diagnosed later than other subtypes.
Nail Unit Melanoma
Nail unit melanoma is a rare variant of cutaneous melanoma which develops underneath the fingernail. It most commonly develops in the thumb or the big toe, and is most common in people between the ages of 50-70. For more information on nail unit melanoma, please refer to the Rare Cancers Australia Melanoma (Nail Unit) page.
Treatment
If cutaneous melanoma is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for cutaneous melanomas may include:
- Surgery (more specifically, a wide local excision or lymph node dissection).
- Radiation therapy.
- Chemotherapy.
- Immunotherapy.
- Targeted therapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.
Risk factors
The biggest risk factor for cutaneous melanomas is exposure to ultra-violet (UV) radiation from the sun or other sources, such solariums (sun beds). Other potential risk factors include:
- A history of childhood tanning and/or sunburn.
- Regular short and intense periods of UV radiation.
- Having over 50 moles on the body, or over 10 on the upper arms.
- Having a lot of unusual moles.
- Being immunosuppressed.
- Having a family and/or personal history of skin cancer.
- Physical appearance, including having:
- Fair skin.
- Lots of freckles.
- Light eye colour (usually blue or green).
- Light hair colour (such as blonde or red).
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
Cutaneous melanomas often appear as unusual moles, freckles, or spots. However, their appearances can vary greatly depending on cancer type, age of the patient and other individual factors. Generally, most types of cutaneous melanomas have characteristics that can be described by the Glasglow 7-point checklist and/or the ABCDEFG of melanoma.
Glasglow 7-point checklist
The Glasglow 7-point checklist is composed of major and minor features of melanomas.
Major features
Major features include:
- Changes in shape, potentially including:
- Increased height.
- Ragged edges.
- Scalloped or notched shape.
- Becoming asymmetrical.
- Becoming scaly.
- Irregular shape, potentially including:
- Increased height.
- Ragged edges.
- Scalloped or notched shape.
- Being asymmetrical.
- Being scaly.
- Irregular colour, potentially including:
- Becoming blotchy.
- Brown, black, red, white, light grey or the colour of your skin.
Minor features
Minor features include:
- Diameter over seven millimetres.
- Inflammation.
- Oozing or bleeding.
- Change in sensation (e.g., becoming painful, elevated, itchy or a new lump).
ABCDEFG of Melanoma
The symptoms of a cutaneous melanoma can also be categorised by this method, which evaluates different features of the potential cancer.
- A: Asymmetry of shape and/or colour.
- B: Border irregularity.
- C: Colour variation and changes.
- D: Diameter.
- E: Elevated or evolving (becoming larger, changing in appearance etc.).
- F: Firm.
- G: Growing.
Not everyone with the symptoms above will have cancer, but see your GP if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a melanoma, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities. More specifically, they will examine the suspicious mole, spot or freckle, and classify it using either the Glasglow 7-point checklist or the ABCDEFG of melanoma.
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), positron emission tomography scan (PET scan) and/or ultrasound, depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage melanomas have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.