What is Melanoma (Skin Cancer)? Causes, Symptoms and Treatment

Melanoma is the most dangerous form of skin cancer, yet also the one most likely to be cured if detected early. Seven in ten cases arise from existing moles — which means you can watch for warning signs yourself.

In this article, we explain exactly what melanoma is, how to use the ABCDE method to examine your skin, what the risk factors are, and which treatment options are available.

What is melanoma (skin cancer)?

Melanoma arises from melanocytes — the cells that produce melanin, the pigment that gives skin its colour. When melanocytes change and grow uncontrollably, they can form a malignant tumour.

Melanoma differs from other forms of skin cancer (such as basal cell carcinoma and squamous cell carcinoma) in having the greatest potential to spread (metastasise) to other organs, including the lymph nodes, lungs and brain. For this reason, early diagnosis is particularly critical.

The good news is that melanoma detected early has a very high cure rate — often above 90% following surgical removal.

What does melanoma look like? The ABCDE method

The easiest way to keep an eye on your skin is to use the ABCDE method to examine moles and new spots:

A — Asymmetry

One half of the mole or spot looks different from the other.

B — Border irregularity

The edges are uneven, jagged, notched or irregular, unlike a normal mole.

C — Colour variation

There are different shades of brown, black, red, white or blue within the same spot. A normal mole typically has one uniform colour.

D — Diameter

The mole is larger than 6 millimetres — about the size of a pencil eraser. However, smaller moles can also be malignant.

E — Evolving (change over time)

The mole changes over time — in size, shape, colour, height, or if it begins to itch, bleed or crust.

Beyond the ABCDE method, watch for "birdshot" patterns of dark brown to black streaks, which can be an early sign of lentigo maligna (a type of melanoma on the face).

Why does melanoma happen?

Ultraviolet (UV) radiation from the sun is the primary cause of melanoma. UV rays damage the DNA in melanocytes and can trigger uncontrolled cell division.

UV radiation and sunburn

Both UVA and UVB rays contribute to the risk. Severe sunburns — especially in childhood and the teenage years — increase the risk significantly, as the skin's immune defences are particularly vulnerable at that time.

Genetics

Hereditary factors play an important role. If you have close relatives with melanoma, your own risk is elevated. Specific genetic mutations (e.g. in the BRAF and NRAS genes) also increase the risk.

Moles

People with many moles (more than 50) or atypical moles (large, irregular moles with unclear borders) have an increased risk. Atypical moles are also called dysplastic nevi.

Who gets melanoma?

Melanoma can affect anyone, but certain groups have a higher risk:

People with fair skin: The lighter your skin and eyes, the greater the risk, because less melanin provides natural protection against UV rays.
People with a family history: Inherited mutations can increase the risk significantly.
People with many moles: More than 50 moles increases the chance that at least one will develop into melanoma.
People with a history of sunburns: Especially sunburns during childhood and the teenage years.
People who use tanning beds: Tanning beds emit concentrated UV radiation and increase the risk significantly.

Note: Melanoma also occurs in darker-skinned individuals and can appear in unusual places such as under the nails, on the palms of the hands and on the soles of the feet — areas not exposed to direct sunlight.

What can you do about melanoma?

Treatment of melanoma depends on how early it is detected. The key to survival is early diagnosis and prompt treatment.

🔬 Early diagnosis (primary melanoma, local)

Surgical removal (excision) is the standard treatment. The thinner the tumour (measured in millimetres), the better the prognosis. With early diagnosis, the cure rate is often above 90%.

🧬 Advanced melanoma (metastatic)

Immunotherapy (e.g. checkpoint inhibitors such as pembrolizumab and nivolumab) has revolutionised the treatment of advanced melanoma and significantly improved survival rates. Targeted therapy against specific mutations (BRAF inhibitors) is also an option.

☀️ Prevention is the best treatment

Use sunscreen with SPF 30 or higher daily, wear protective clothing, avoid direct sun during the strongest hours, and avoid tanning beds entirely. Examine your skin once a month.

Medical classification: Melanoma is classified as C43 (or ICD-11: 2C30 Melanoma of skin) in the WHO's International Classification of Diseases. It is characterised by malignant tumours from melanocytes, often with asymmetry, colour variation and irregular borders.

Frequently asked questions

Is melanoma dangerous?

Melanoma is the most dangerous form of skin cancer because it can spread to other organs. But detected early, it is often fully curable. The risk increases significantly the deeper the tumour is.

How do I examine my skin myself?

Examine your entire skin from head to toe once a month — including the scalp, under the nails, between the toes and on the soles of the feet. Use a mirror for hard-to-reach areas. Photograph your moles and compare with previous images.

When should I contact a dermatologist?

Contact a dermatologist immediately if you find a mole that meets one or more ABCDE criteria, if a mole is changing, or if you have a family history of melanoma. Regular screening is recommended for people in high-risk groups.

Get a skin assessment within 48 hours

Unsure about a mole? Upload photos via the SKIND app and get an assessment from a certified dermatologist — no hospital waiting list.

Download the app

Disclaimer: This article is for informational purposes only and does not replace professional medical advice. Always consult a dermatologist for personal guidance if you suspect melanoma.