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Skin Cancer Explained

Cancerous moles – what do they look like?

Your guide to the signs of skin cancer in moles and how to tell if a mole is cancerous – with pictures.
A person examines their skin with a handheld device, assessing for signs of cancerous moles
MoleMap Team
August 2, 2021
12 minutes

Wor­ried about a mole that’s new, chang­ing or just looks unusu­al? Then you’re in the right place – this arti­cle out­lines the 9 com­mon signs of can­cer­ous moles, with help­ful pic­tures so you know the symp­toms to look for.

Most moles are harm­less but unfor­tu­nate­ly some aren’t – and it can be very dif­fi­cult to tell if a mole is can­cer­ous with an untrained eye. If you have a mole that’s show­ing some of the signs of skin can­cer below – or if you’re just not sure about it, book an expert full body mole check as soon as pos­si­ble — because the ear­li­er a can­cer­ous mole is detect­ed, the bet­ter the chances of suc­cess­ful treatment.

Read on to find out what warn­ing signs to look for and when you should get a sec­ond opinion…

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First­ly, what makes a mole cancerous?

Most moles or ​‘nevi’ are fair­ly harm­less. In gen­er­al, most Aus­tralian adults typ­i­cal­ly have some­where between 10 and 40 com­mon, or non-malig­­nant, moles on their body (note that if you have 50 or more moles, you may have a high­er risk of melanoma).1

Moles are essen­tial­ly clus­ters of melanocytes, the pig­ment-pro­duc­ing cells that increase the pro­duc­tion of melanin to pro­tect the skin against poten­tial­ly harm­ful UV

rays. Melanoma occurs when these melanocytes mutate and begin to divide uncontrollably.

The most com­mon cause of can­cer­ous moles is exces­sive expo­sure to UVA and UVB light (i.e. dam­age from the sun and sun beds), so the best thing you can do for your skin health is reduce your sun expo­sure, fol­low the Sun­Smart guide­lines – and have reg­u­lar, pro­fes­sion­al skin checks .2

What do nor­mal (non-can­cer­ous) moles look like?

A com­mon mole, also known as a ​‘nevus’, is a non-malig­­nant growth on the skin that often appears dur­ing child­hood or ado­les­cence. They are usu­al­ly pink, brown, or tan in colour and can take many dif­fer­ent forms, includ­ing freck­les, moles, skin tags, and seb­or­rhe­ic ker­atoses. Com­mon moles tend to look alike – they’re uni­form in shape and even coloured, rang­ing from 1mm to 10mm in size.

Almost all of us have moles, although they’re more preva­lent in those with lighter or freck­ly skin. Moles are not nor­mal­ly present at birth, but tend to appear in child­hood and ear­ly teenage years. Some moles may also light­en or dark­en with time as we age – espe­cial­ly with sun expo­sure. Gen­er­al­ly speak­ing, nor­mal moles are sta­ble — they’ll look the same a year from today.

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9 signs that a mole may be cancerous

When self-check­ing your skin (or the skin of a loved one), look out for any­thing NEW, CHANG­ING, or UNUSU­AL on both sun-exposed and sun-pro­tect­ed areas of the body.

Melanomas com­mon­ly appear on the trunks of men and the legs of women, but they can occur any­where — even in places that nev­er see the sun, like on the but­tocks, the soles of the feet, and the gen­i­tal area.4

Oth­er types of skin can­cer such as basal cell car­ci­no­ma and squa­mous cell car­ci­no­ma most com­mon­ly devel­op on parts of the body that receive high or inter­mit­tent sun expo­sure, such as on the face, scalp, neck, arms, shoul­ders and back.5

Look out for these 9 com­mon signs of skin can­cer when you check your skin:

  1. You notice a new mole — most moles appear appear dur­ing child­hood and ado­les­cence, so any new moles that appear if you’re aged over 25 (and espe­cial­ly if you’re aged over 50) could poten­tial­ly be can­cer­ous and should be checked out, espe­cial­ly if you notice the mole chang­ing – see below.6

  2. You have a mole that’s increas­ing in size –moles can grow slow­ly as you get old­er, but any rapid or sud­den change is some­thing to be con­cerned about and may indi­cate the pres­ence of fast-grow­ing melanoma. Moles that are larg­er than 6 mm in size (the diam­e­ter of a pen­cil eras­er) should be checked reg­u­lar­ly. Can­cer­ous moles can be small­er, but they don’t usu­al­ly stay that way and will grow over time.
  3. You have a mole that’s asym­met­ri­calin shape - most nor­mal, non-can­cer­ous moles tend to appear as a per­fect cir­cle — where­as most prob­lem moles are asym­met­ri­cal or lop-­sided. Asym­me­try in moles is one of the ​‘red flags’ for skin can­cer, so ensure you have any unusu­al­ly-shaped moles checked by your GP or skin can­cer detec­tion service.
  4. The edge of a mole has become notched or ragged – most nor­mal or com­mon moles tend to have sharp, well-defined bor­ ders. If your mole looks notched or ragged, or seems to spread or grad­u­al­ly blur into the sur­round­ing skin, it would pay to get it skin check. The bor­ders of an atyp­i­cal (can­cer­ous) mole are often irreg­u­lar and/​or ​‘hazy’ — symp­toms that become more pro­nounced as time goes on.
  5. You have a mole that’s dark­en­ing or chang­ing in colour – Most nor­mal moles are tan, brown, or the same colour as your flesh and are also uni­form in appear­ance. One part of the mole isn’t nec­es­sar­i­ly lighter or dark­er than any oth­er. If a mole appears to be mul­ticoloured — in that it has areas that are dark brown, blue, black or white, and even red — you should get a sec­ond opin­ion from MoleMap­ or your GP. This can be a sign of super­fi­cial spread­ing melanoma, the most com­mon form of melanoma.
  6. A mole is becom­ing raised or devel­ops a lump with­in it – this can be a symp­tom of nodu­lar melanoma, a par­tic­u­lar­ly fast-grow­ing and dan­ger­ous form of melanoma. The key give­away is that it’s raised, often sym­met­ri­cal, firm to touch, and is chang­ing or grow­ing pro­gres­sive­ly. Any raised, firm or grow­ing spots should be pro­fes­sion­al­ly checked as a precaution.
  7. The sur­face of a mole is becom­ing rough, scaly or ulcer­at­ed – small, rough or scaly patch­es on your skin can be actinic ker­ato­sis (solar ker­ato­sis) which is gen­er­al­ly caused by too much sun, and com­mon­ly occurs on the head, neck, or hands, but can be found else­where. They can become can­cer­ous over time, so it pays to get these checked reg­u­lar­ly for changes. How­ev­er, if a mole is ulcer­at­ed, you should get it checked imme­di­ate­ly – it is high­ly like­ly to be a melanoma and has a high­er risk of spread­ing than oth­er melanomas.7

  8. You have a mole that’s itchy, tin­gling, weep­ing or bleed­ing - Most can­cer­ous moles don’t hurt, but there are warn­ing signs, includ­ing itch­i­ness, tin­gling, bleed­ing or weep­ing. Just like the rest of the skin on your body, a mole can become itchy, or get injured and bleed as a result of injury – that’s usu­al­ly noth­ing to wor­ry about. How­ev­er, moles that bleed or ooze flu­id with­out being injured may be cause for con­cern – you should get these checked by experts just as soon as you can.

  9. You have a mole or spot that look dif­fer­ent from the oth­ers – the ​‘ugly duck­ling’. Most nor­mal moles on your body will look sim­i­lar in appear­ance, while melanomas often stand out like ugly duck­lings in com­par­i­son. These can be larg­er, small­er, lighter or dark­er when com­pared to sur­round­ing moles – or they may be iso­lat­ed with­out any sur­round­ing moles. That’s why it’s impor­tant to not only check your moles, but also to com­pare them – this is a vital part of any pro­fes­sion­al full body mole check and mon­i­tor­ing ser­vice such as a Full Body MoleMap.

Oth­er help­ful guides devel­oped by der­ma­tol­o­gists for detect­ing skin can­cer are the ABCDE and EFG rules – you can check them out here. You can also find our help­ful guide for self-check­ing your skin. And read on for the answers to oth­er fre­quent­ly asked ques­tions about can­cer­ous moles…

Can a nor­mal mole become cancerous?

The short answer is yes. For adults, new moles and sud­den changes to exist­ing moles can be a sign of melanoma. Accord­ing to Yale School of Med­i­cine, approx­i­mate­ly 70 per­cent of melanomas appear on nor­mal skin, while 30 per­cent orig­i­nate in a pre­-ex­ist­ing mole in which changes in col­or, size, and/​or shape have occurred.8

Can I detect a can­cer­ous mole myself?

We thor­ough­ly rec­om­mend reg­u­lar self-checks so you can get to know your skin and moles. But please bear in mind that no mat­ter how vig­i­lant you are about check­ing your skin, many of the signs of skin can­cer are very dif­fi­cult to see with an untrained eye — espe­cial­ly in the ear­ly stages.

Note also that a sin­gle exam­i­na­tion of your skin isn’t enough to assume a mole will remain nor­mal. One of the major indi­ca­tions of can­cer­ous moles is that they con­tin­ue to grow and change shape and colour, and these symp­toms gen­er­al­ly become more pro­nounced over time – which is why we rec­om­mend a mole check to track changes in your skin and moles over time.

Can a doc­tor tell if a mole is can­cer­ous just by look­ing at it?

If the skin can­cer is start­ing to advance, then yes, the symp­toms may be obvi­ous to the naked eye. How­ev­er, the ear­ly signs of melanoma skin can­cer aren’t always vis­i­ble at a glance.

That’s why a group of der­ma­tol­o­gists pio­neered the Full Body MoleMap, which involves tak­ing high-res­o­lu­tion, close-up images of any at-risk moles and spots, and com­par­ing them at sub­se­quent appoint­ments. This method­ol­o­gy can improve the chances of detect­ing any poten­tial skin can­cers much ear­li­er than visu­al checks – because the ear­li­er skin can­cer is found, the bet­ter the chances of beat­ing it.9

What are the risk fac­tors for get­ting can­cer­ous moles?

The most com­mon risk fac­tors for melanoma skin can­cer are:

  • fair and/​or freck­ly skin that burns easily
  • fair, blonde or red hair
  • hav­ing been sun­burnt in the past or used sunbeds
  • hav­ing a lot of moles (50+)
  • being over 50 years old
  • lead­ing an out­door lifestyle or hav­ing high dos­es of inter­mit­tent sun (e.g. on holiday)
  • a per­son­al or fam­i­ly his­to­ry of skin can­cer, espe­cial­ly melanoma
  • Cer­tain med­ica­tions, includ­ing immune-sup­pres­sion med­ica­tions.10

If you’re not sure of your risk lev­el, take this quick skin can­cer risk quiz. And if you think you may be at high­er risk, we high­ly rec­om­mend a com­pre­hen­sive skin check every year.

How often should I get my skin checked for can­cer­ous moles?

The lat­est sta­tis­tics from the US show that patients whose melanoma is detect­ed ear­ly have a 99% five-year sur­vival rate. This drops to 66% if melanoma reach­es the lymph nodes, and 27% if it spreads to dis­tant organs.11 All good rea­sons to have a skin cancer check every year.

At Australia skin cancer clinic like MoleMap, we recommend

  1. A self-check every 3 months (or every month if you’re high risk) – you can down­load our help­ful self-check guide here.
  2. A GP check every 6 months — in between your reg­u­lar mole-map­ping appointments.
  3. A Full Body MoleMap or Skin Check every year – see which ser­vice is right you here.

Remem­ber, if you’re wor­ried about a mole, don’t chance it: check it. It may just save your skin – and your life.

1. Skin.cancer.org: https://www.skincancer.org/skin-cancer-information/melanoma/melanoma-warning-signs-and-images/ 2. Melanoma Institute Australia: https://www.melanoma.org.au/understanding-melanoma/what-is-melanoma/ 3. Skin.cancer.org: https://www.skincancer.org/risk-factors/skin-type/ 4. Melanoma Institute Australia: https://www.melanoma.org.nz/facts-risk-factors 5. Cancer Council of Australia: https://www.cancer.org.au/about-cancer/types-of-cancer/skin-cancer.html. 6. Melanoma Institute Australia: https://www.melanoma.org.au/understanding-melanoma/melanoma-facts-and-statistics 7. Melanoma Institute Australia: https://www.melanoma.org.au/understanding-melanoma/what-is-melanoma/ 8. https://medicine.yale.edu/dermatology/dermsurg/Chapter%2022%20Melanoma_36878_284_5_v2.pdf 9. Melanoma Institute Australia: https://www.melanoma.org.au/understanding-melanoma/what-is-melanoma/ 10. Melanoma NZ: https://www.melanoma.org.nz/facts-risk-factors 11. Skin.cancer.org: https://www.skincancer.org/skin-cancer-information/melanoma/melanoma-warning-signs-and-images/

MoleMap Team

At MoleMap we check, detect and treat skin cancer. Find out how you can protect your skin at your nearest MoleMap skin cancer clinic.

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MoleMap specialises in skin cancer detection, diagnosis, proactive monitoring and treatment. Want the best protection against melanoma and other skin cancers? Get your skin and moles checked early and often at a MoleMap skin cancer clinic.