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Spotting the Signs: How to Identify Cancerous Moles

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It is a well-known fact that the early detection of any sort of cancer often results in a better prognosis. This is also the case with skin cancer. 

Melanoma can be diagnosed if it is detected early and treatment is sought before it becomes metastatic. This is when cancer cells spread from their original location to other parts of the body. 

Aside from seeking advice from medical professionals, regular self-examinations are one of the best ways to notice any changes in the appearance of your skin. In fact, a Queensland study found that more than 40% of people with melanoma had detected it themselves. This is why it's essential to get to know your skin and understand what to look for when checking your skin and how to identify cancerous moles. 

Understanding Moles

Moles are very common and most people have around 50 on their bodies. But what exactly causes a mole to appear and do they carry a cancer risk? 

What are moles?

Unlike a freckle, which is normally flat, moles are typically raised. Moles are evenly coloured spots ranging in size from 1-10mm. While most are nothing to worry about, having a high number of moles and freckles is a skin cancer risk factor.

Types of moles

There are three main types of moles. The risk of these turning into melanoma depends on several factors. 

  • Acquired or common moles: These are harmless and can appear at any time. 
  • Dysplastic or atypical moles: There is usually a family history of these sort of moles. They can vary in colour from tan and brown to pink. In terms of shape, they can have an irregular or notched border or edges and are about the size of a pencil eraser or around 6mm in diameter. Their texture can vary from smooth to scaly and rougher than a normal mole. Having a lot of these types of moles increases your risk of developing melanomas. 
  • Congenital mole: Also known as birthmarks. These can come with a greater risk of malignancy in adulthood. 

How moles develop

Moles typically appear in childhood and can be found anywhere on the body. They form on the skin when pigment-producing cells called melanocytes cluster, causing moles to appear on the surface of the skin. Melanocytes produce melanin, which gives the hair, eyes and skin their colour. 

The difference between cancerous and non-cancerous moles

A normal mole will be evenly coloured and will stay the same for a long time. If a mole is changing - if it looks or feels different - this is the time to have it checked by a doctor as there is a chance it has become cancerous. 

Because cancerous moles can have no symptoms, it's also important to seek advice if you have a mole on your body that doesn't look like the rest or if it becomes sore and fails to heal.  

The appearance of a new mole is another reason to see a doctor. 

A dark patch under the nails on fingers and toes and in the mouth can also be a cancer warning sign.

6 signs of cancerous moles

Not all skin cancers will have the following symptoms but these are the main ones to watch for signs of cancerous moles. If you notice any of these changes, it is important for your health to see a doctor straight away. 

1. Itching or bleeding

If a mole begins oozing or bleeding or has begun to itch or cause pain. 

2. Rapid mole growth

If a mole appears to change shape, become bigger or changes in elevation, this could also indicate early stage melanoma. 

3. Changes in texture

Cancerous moles can sometimes become scaly or appear lumpy or bumpy. 

4. Ulceration

Moles with ulceration could indicate that the layer of skin is breaking down and a tumour is spreading.  

5. Pigment spreading beyond the mole

You should also look out for redness or swelling beyond the border of a mole and colour spreading into the surrounding skin. 

6. Colour

Another warning sign is when moles change in colour, have a different shade or become blotchy. 

Woman checking her skin for skin cancer in a mirror

How to examine your moles at home

  • Stand in front of a full-length mirror and ask a friend or person you trust to help examine places you cannot see well, such as your back.
  • Look for skin changes such as those listed above.
  • Examine all parts of your body, beginning with the scalp and work your way down. Pay close attention to parts of your body that are exposed to UV radiation such as your head, arms and legs. But don't forget to check the areas that may often be protected from the sun, such as your chest.
  • Check your throat, the palms of your hands, your underarms and the backs of your arms. Don't forget to check between your toes and the soles of your feet, as well as under each fingernail and toenail. 
  • Use a hand-held mirror to examine your scalp and neck and any other hard-to-see areas, such as the buttocks. 
  • Note down if you see something of concern such as new growths and follow this up with a doctor.
  • Make self-examinations a regular practice.

Don't forget to consider your risk factors including skin type, a history of sunburn, a family history of skin cancer, level of sun exposure and the extent of sun protection. 

An easy technique to follow when checking your skin is to follow the abcde technique to know what changes to look for. 

Spot the ABCDEs of cancerous moles

  • Asymmetry
  • Border
  • Colour
  • Diameter
  • Evolving


If you were to draw a line through the middle of your mole and both halves do not look the same, it is asymmetrical. 


Look for changes in a mole's borders such as spreading or scalloped or irregular edges. 


Keep an eye out for blotchy spots in the colour of the mole, the presence of many colours or a recent change in its colour. 


The size of the lesion could be a concern if it is larger than 6mm (about the size of a pencil eraser). 


Cancers grow and change constantly, so look for differences or growth in a mole's size, shape or thickness. 

Doctor inspecting man for skin cancer

When to see a doctor for your mole

If you notice any of the above signs of cancerous moles, it's important to have your mole checked by a doctor as soon as possible. As well as being quick and non-intrusive, a mole check can give you peace of mind. 

If your doctor suspects a mole could be cancerous, a biopsy will take place. This is when a small number of skin cells are taken for further examination. From there, your doctor will recommend the best course of treatment. This could be ongoing skin checks at regular intervals or may involve a simple cancer treatment such as simple surgery. If your cancerous mole has evolved, it may involve a more complex therapy such as chemotherapy or radiation, which can bring side effects. This is why early detection of a cancerous mole is so important. 

While prevention is by far the best way to avoid moles becoming cancerous, it's also imperative to look out for the warning signs and cancer symptoms listed above. Also, be sure to raise anything you see on your skin that concerns you with a doctor who specialises in skin cancer detection and treatment. 

The doctors at SunDoctors are extensively trained in cancer treatments and have the experience to provide you with an accurate diagnosis. Put your mind at ease and book a mole check today. 

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