About melanoma

There are several different types of melanoma that a patient may experience. These include:

• Superficial spreading melanoma
• Amelanotic melanoma
• Nodular melanoma
• Lentigo maligna melanoma
• Desmoplastic melanoma
• Acral lentiginous melanoma
• Mucosal melanoma
• Uveal melanoma

Superficial spreading melanoma

Superficial spreading melanoma is the most common type of melanoma and is seen in 60-70% of patients diagnosed with melanoma.⁴ The malignant cells for this type of melanoma tend to stay in the epidermis in an ‘in-situ’ phase for a prolonged period. This type of melanoma can be characterised by its radial growth across the skin, with the nodules appearing discoloured and flat. However, if the nodules lack pigment, this can be described as amelanotic melanoma, a rare type of melanoma seen in around 8% of melanoma patients.⁴ The superficial spreading melanoma type can develop anywhere in the body, but it’s most noted on the central parts of the body for men and the legs for women.⁴

Nodular melanoma

Nodular melanoma is the second most common subtype of melanoma and can be seen in 15-30% of melanoma cases.⁴ The malignant cells can develop in any part of the body and grow quite quickly into the deeper layers of the skin. This type of melanoma is characterised by its raised uniform blue-black or pink-red nodules.

Lentigo maligna melanoma

Lentigo maligna melanoma accounts for 5-15% of all melanoma cases and occurs mainly on sun-damaged skin.⁴ It can be characterised by its slow radial growth and invasive nature.

Desmoplastic melanoma

Desmoplastic melanoma is a rare subtype of melanoma and results from the growth of fibrous or connective tissues. The overall incidence rate is 2.0 per million, with an annual percentage increase of 4.6% per year. Desmoplastic melanoma can develop anywhere on the body but is most commonly found on the head and neck (53%) and trunk (20%) , and the nodules often resemble fibrotic scarring. This type of melanoma is highly invasive and is usually associated with nerve invasion.⁸

Acral lentiginous melanoma

Acral lentiginous melanoma accounts for 5-10% of melanoma cases and is the most common type of melanoma presented in people of colour.^4,5 This type of melanoma is usually found on the palms of the hands and soles of the feet and usually appears black or brown in colour.

Mucosal melanoma

Mucosal melanoma is a rare type of melanoma and accounts for approximately 1.4% of melanoma cases. Mucosal melanoma malignant cells develop in the mucous membrane, the layer of tissue that covers internal organs’ surface and is usually found in the mucosal tissues of the head, neck, genital or anorectal mucosa.⁴

Uveal melanoma

Uveal melanoma is another rare type of melanoma and accounts for 2-8 incidences of melanoma per million. The malignant cells in this type of melanoma develop in either the iris, ciliary body or the choroid, with more than 90% of cases involving the choroid.¹⁰

Summarising table of subtypes of melanoma^3-10

Melanoma is the leading cause of skin cancer deaths in the UK, claiming the lives of around 2,300 people each year. Its incidence rates have more than doubled (140%) in the UK since the early 1990s, with rates having doubled (106%) and almost tripled (186%) in females and males, respectively (2016-2018)¹

Summarising table of subtypes of melanoma^3-10

Melanoma Skin Cancer, European Age-Standardised Mortality Rates per 100,000 Population, UK, 1971-2018¹³

The main risk factor for melanoma is exposure to UV radiation. Other risk factors for melanoma include:

UV radiation exposure

The risk of developing melanoma is 60% higher in people who are regularly exposed to high-intensity sunlight compared to those who have limited exposure to sunlight.¹⁵ In the UK, ~86% of melanoma cases diagnosed in 2010 were attributed to excessive exposure to UV radiation.¹⁴ The risk of developing melanoma is also increased by sunburn. People who experience sunburn once every two years are three times more likely to develop melanoma than people who have never experienced sunburn.¹⁶

Sunbed use is associated with a 15% increase in melanoma risk versus never having used a sunbed. Furthermore, the risk of developing melanoma is over four times higher in sunbed users aged 18-29 years versus 30-39 years.¹⁷

Skin type and colour

People with very fair skin (skin phototypes I) are more than twice as likely to develop melanoma than people with much darker skin (skin phototype IV). The risk of developing melanoma is also increased in people with red/ blond hair or blue/green eyes compared with darker hair and dark eyes.¹⁸

Age

Melanoma can affect people of all ages but is mainly diagnosed in older people. This is most likely due to accumulated cell damage over time. Incidence rates for melanoma in the UK are highest in people aged 85 to 89.¹ However, each year between 2016 and 2018 over a quarter (29%) of all new melanoma diagnoses in the UK were in people aged ≥75 years.¹

Family history and genetics

Inherited risk of melanoma accounts for around 10% of new cases of melanoma. Compared with people with no family history of melanoma, the risk of developing melanoma is more than twice as high in people with a close relative who has had melanoma.

In addition, the risk of developing melanoma is higher in people who carry the cyclin-dependent kinase inhibitor 2A (CDKN2A) mutation; 20-40% of families with melanoma carry the mutated gene.

Moles (naevi or atypical naevi)

Moles are common skin growths that are usually brown or black in colour and are caused by clusters of pigmented cells. Most moles are genetically determined and begin to appear during early childhood and adolescence. However, the risk of developing melanoma is nearly seven times higher in people with many moles compared with those with fewer moles.¹⁵ In addition, the risk of developing melanoma is around four to ten times higher in people who have atypical naevi (atypical moles).¹⁵

Birthmarks (congenital naevi)

Birthmarks are colour marks on the skin and can be made up of different types of cells. Most birthmarks carry a low risk of developing into melanoma. However, there is a rare type of birthmark, called a giant congenital melanocytic naevus, which can develop into a melanoma if it is larger than 20cm.