What are Melanocytes?
Melanoma is the deadliest form of skin cancer as by the time it is usually detected it has often already spread through other areas of the body and is no longer localised to the skin.
The skin has two main layers, the upper layer called the epidermis and the inner layer called the dermis. In the epidermis are the cells called melanocytes that are responsible for production of melanin, the skin’s source of pigment.
Are Moles Cancerous?
Melanocytes sometimes congregate and form moles (nevi), a common skin feature but usually harmless and not cancerous. Moles can, however, be wrongly identified and any newly observed moles or changes in the size, texture, colour, or shape of moles warrants further investigation.
These dysplastic nevi are a risk factor for melanoma as are multiple moles on a person (usually more than fifty). Despite stories about the dangers of cutting a mole there is no clear evidence that the risk of skin cancer is increased when a mole is cut, although unexplained bleeding of a mole definitely requires urgent medical evaluation.
Melanoma skin cancer detection received a boost in recent months with the approval of MelaFind, a diagnostic tool created by Mela Sciences. The hope is that this melanoma detector can increase early detection rates and reduce fatalities associated with the deadliest form of skin cancer.
Most skin cancers can be cured if found early enough which is why frequent skin checks are essential. Harder to reach places, such as the back, neck, ears, and legs can be checked using a mirror or by having a partner or friend help check the skin for abnormalities.
Early Signs of Melanoma
Birthmarks or moles that change shape, size, texture, or colour may indicate skin cancer, as can new skin growths such as nodules that begin as pale, pearly growths. These growths may then progress to larger, crusty red skin patches, sometimes scaly but usually clearly defined.
Melanoma may also be indicated by sores on the skin that fail to heal, or any patch of skin that bleeds, swells, oozes, itches, or is red and bumpy. As there are so many skin conditions fitting one or more of these descriptions, such as eczema, psoriasis, and contact dermatitis it is all too easy to miss the early signs of skin cancer and simply apply creams and ointments in the hope such symptoms disappear.
Specific things to watch out for when checking for melanoma include:
- A new and unusual skin growth
- Changes in the skin on the hands, face, neck, arms and legs (more often exposed to the sun
- Moles that are asymmetrical
- Moles with jagged edges or irregular shape
- Moles which are more than one colour, i.e. with black, brown, blue, white, grey, or pink patches
- Large moles more than 6mm in diameter
- Itchy moles
- Moles that change in texture, becoming hard or lumpy for example
- Moles that bleed or ooze.
Skin Cancer Biopsy
In order to diagnose melanoma a skin biopsy needs to be performed. This will follow a physical examination and the taking of the patient’s medical history including family history. A biopsy usually means the removal of the entire skin growth with a sample then taken of the removed tissue for testing. Where the growth is not able to be removed in full the doctor will take an incisional biopsy (in contrast to the routine excisional biopsy) in order to have the sample tested.
Biopsies are usually performed with a local anaesthetic to numb the area and where needed the skin will be sutured afterwards. Such skin biopsies are done as an outpatient procedure in hospitals or, more usually, in the doctor’s office.
Testing the Biopsy for Cancer
Laboratory technicians will test the skin sample removed during biopsy in order to study the rate of growth and the cell division for signs of cancer. Where it is thought the melanoma may have spread into deeper and surrounding tissues the doctor may then decide on a biopsy of nearby lymph nodes, or wish to perform imaging studies or blood tests based on the biopsy results.
Stages of Melanoma Skin Cancer
Following a confirmed diagnosis of melanoma skin cancer the oncology team will determine the stage of the cancer. Different cancer stages describe the degree to which the cancer has spread beyond its original location and the size of the tumour; there are five stages with the least complicated 0 stage melanoma where the cancer is localised in the top layer of the skin and has not spread (in situ cancer).
Stage 1 melanoma is where the cancer has not spread to nearby lymph nodes and remains smaller than 1 mm with or without ulceration (or is 1-2 mm without ulceration).
Melanoma that remains in the surface layers of the skin and has not spread to the lymph nodes but is 1-2 mm with ulceration or larger than 2 mm with or without ulceration is known as stage 2 skin cancer.
Later Stage Melanoma
Stage 3 melanoma describes skin cancer that has spread to the surrounding skin and one or more nearby lymph nodes, whereas stage 4 skin cancer means the melanoma cells have spread to other areas of skin, distant lymph nodes and possibly other bodily organs such as the lungs or bones. Determining the stage of melanoma is important in deciding what kind of skin cancer treatment to instigate.
Melanoma is most common on the back in men and on the back of the legs in women with more than 5,500 new cases reported in Canada in 2011, more than 10,000 new cases in the UK, and over 76,000 estimated in 2012 in the US (with nearly 10,000 melanoma deaths).
Of the cases reported in the US, around 16% are considered late stage malignant melanoma with a 5-yr mortality rate of more than 50%, making early detection extremely important for reducing death from melanoma.
Causes of Melanoma
Melanoma has no single cause, but there are risk factors that increase the likelihood of this type of skin cancer occurring. Ultraviolet light exposure is a major risk factor, whether this is from the sun or from tanning beds and sun lamps producing artificial UV light. People who have skin that burns easily or freckles easily are at an increased risk of melanoma, as are those with light skin, eyes, or hair or who suffered severe sunburn in childhood.
Where a person has more than fifty moles on their body there is an increased likelihood of melanoma occurring, and if those moles are unusually shaped or appear larger or darker than other moles the risk is also increased. Those who have previously suffered melanoma are also at added risk, as are those with a family history of this type of skin cancer although some people develop melanoma with none of these risk factors present. In other forms of skin cancer, such as squamous cell carcinoma, it is thought that particular detoxifying cells may play a role in the development of skin cancer although no such link has been found as a cause of melanoma.
Read more about melanoma treatment.