What Does a Cancerous Mole Look Like? (Warning Signs You Shouldn’t Ignore)
- Dr Duncan Lowe
- May 31
- 2 min read
Quick Answer
Most moles are harmless, but it's important to know the warning signs of melanoma. In this guide, we'll explain what a cancerous mole can look like, when to seek advice, and what happens during a professional skin assessment.
A cancerous mole (melanoma) often looks asymmetrical, uneven in colour, irregular in border, or changing over time. If you notice a mole evolving, itching, bleeding, or becoming different from others, it should be checked promptly.
What Is a Normal Mole?
Most moles are harmless. Typically, they are:
Round or oval
Even in colour (usually brown)
Small (under 6mm)
Stable over time
Warning Signs of a Cancerous Mole (ABCDE Rule)
Use this simple guide:
A – Asymmetry: One half doesn’t match the other
B – Border: Edges are irregular or blurred
C – Colour: Multiple colours (brown, black, red, white)
D – Diameter: Larger than 6mm
E – Evolving: Changing in size, shape, or colour
The most important sign is change.
Other Symptoms to Watch For
Itching or tenderness
Bleeding or crusting
Rapid growth
A mole that looks very different from others (“ugly duckling sign”)
When Should You Get a Mole Checked?
You should seek assessment if:
A mole changes over weeks or months
You’re unsure whether it’s normal
You have a personal or family history of skin cancer
Early detection dramatically improves outcomes.
Many patients attending our Glasgow clinic tell us they delayed getting a mole checked because they assumed it was "probably nothing". In reality, melanoma is often first detected because someone noticed a subtle change and decided to seek advice early.
What Happens During a Skin Check?
At your appointment:
The mole will be examined clinically
A dermatoscope may be used (magnified imaging)
If needed, removal with histological analysis can often be arranged quickly
FAQs
Is every unusual mole cancer? No - many are benign, but it’s important to check.
Is melanoma common? It’s one of the more serious skin cancers and cases are rising in the UK, but early treatment is highly effective.
Should I wait and see if it changes more? No - if you’re concerned, it’s best to get it assessed early.
Can I book a mole check even if I'm not sure it's serious? Yes. Many people attending our Glasgow clinic are seeking reassurance rather than treatment. If a mole has changed or is causing concern, a professional assessment can help determine whether any further investigation is needed.
Concerned About a Mole?
If you're concerned about a changing mole, don't ignore it. Most skin lesions prove to be harmless, but early assessment is the safest approach.
At Glasgow Skin Specialists, we provide expert mole assessments, skin cancer checks, and treatment for patients across Glasgow and the West of Scotland. If you're worried about a mole, we're here to help.
Find out more on our skin cancer treatment and melanoma website pages.
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