What does a cancerous mole look like?

By Ash 18th August 2021 Category: Advice

What does a cancerous mole look like?

It is important to understand what is meant by ‘cancerous’. Cancers, including those affecting the skin, are characterised by cells that replicate at an abnormal rate, this leads to the formation of a tumour. A fundamental concept to understand is the distinction between benign and malignant tumours.

  • Benign tumours are non cancerous and do not have the ability to spread (metastasize) to other areas of the body.
  • Malignant tumours are capable of invading the tissue surrounding them as well spreading to distant sites (metastasize)

It is the malignant tumours that are often referred to as cancerous.

How serious is skin cancer?

Skin cancers are categorised as either melanoma or non-melanoma. Collectively, these cancers are amongst the most common types of cancer, with melanoma being the 5th most common in the UK and responsible for 90% of all skin cancer-related deaths. It is predicted that melanoma will account for 5% of all cancers in the UK by 2030, and non-melanoma skin cancer rates have more than doubled over the past 30 years.

Clearly then it is important to be able to recognise the early stages of skin cancer so that treatment can be initiated as soon as possible, this is because skin cancers diagnosed at an earlier stage are more likely to respond to treatment and be cured. In fact, 99% of people diagnosed with stage 1 melanoma in the UK survive for 5 years or more. However, sadly only 53% of those diagnosed with stage 4 melanoma in the UK survive for 1 year.

Skin cancers present as lesions, or nevi, on the skin which are highly variable in appearance, these lesions are what we call moles. You can read about the causes of moles here.

What does a normal mole look like?

Most people have moles on their skin and it is good practice to self monitor or seek professional help for monitoring if that is easier . The usual questions to ask when monitoring are “is this normal?, “is it new?” and “has it changed?”’ Being aware of the signs of normality can be helpful in diffusing some of the anxiety in this situation.

Normal moles are often symmetrical, have a smooth regular border, and are of a consistent colour.

What does a cancerous mole look like?

There are two important methods that can be used to assess whether or not a mole is abnormal: The ABCDE model and the Ugly Duckling sign.

The ABCDE model

The ABCDE mnemonic is used in the clinical setting to help decide whether a mole should be closely monitored or investigated further. The rule is most useful for recognising melanoma. The model considers 5 characteristics relating to how the mole looks and how it changes over time.

It is important to mention that not every melanoma will conform to all criteria of the ABCDE model, for example, melanomas that develop from normal skin rather than an existing mole could well be smaller than 6mm in diameter when they are discovered.


Here we will look at some melanoma examples and apply the ABCDE method. It can be helpful to see real-life cases of melanoma to understand some of the things you could be looking for when performing your own mole checks at home.

Example 1:

A: This mole is asymmetrical
B: The border is irregular
C: There is variation in the colour of the mole including red and brown areas.
D: This mole is large in diameter
E: We would need more information to assess evolution, which is why it is important to consult an expert if you are concerned about any of your moles.

Example 2:

(Source: Skin Cancer Foundation)

A: There is asymmetry with the left side being much thicker than the right.
B: The border is irregular
C: There are various shades of brown and black
D: The scale shows that the mole is more than 6mm in diameter

The Ugly Duckling sign

Moles on the skin of the same individual often resemble one another, and potentially cancerous moles are often different from the others and stand out from the crowd, just like an Ugly Duckling.

Other types of skin cancer

Even though malignant melanoma has the highest mortality rate of all skin cancers, there are other types of skin cancer. These are the non-melanoma skin cancers and most commonly include:

  • Basal cell carcinoma
  • Squamous cell carcinoma

Basal cell carcinomas are variable but can appear as pearly pink or white nodules commonly occurring in the head, neck, trunk and limbs. Example shown in image 1.

Squamous cell carcinomas often arise on areas of the skin that have been exposed to the sun such as the face, scalp, arms and neck. They can appear firm and crusty as shown in image 2.
1: Basal cell carcinoma (Source: National Cancer Institute, Creator: Kelly Nelson, MD)
2: Squamous cell carcinoma (Source: National Cancer Institute, Creator: Kelly Nelson, MD)

3: Malignant melanoma (Source: National Cancer Institute, Creator: Laurence Meyer, MD, PhD, University of Utah Health Sciences Center)

How do I get my moles checked?

Although the methods mentioned above can be useful, they are certainly not fool-proof and are more useful when used by experienced clinicians, especially dermatologists.

If you are concerned about any of your moles, The Mole Clinic offers the nation’s most advanced, innovative mole screening services including mole diagnostic report for single moles , full body skin check for a top-to-toe examination and full body mole mapping if required.

If you are unable to visit a clinic there are some at home services too.

Click here to find your nearest clinic and book your consultation.

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