Skin Cancer Signs
The changes in moles and skin lesions that warrant assessment.
Last revised
Key takeaways
- ABCDE: Asymmetry, Border, Colour, Diameter, Evolving
- Most important single feature: change over weeks or months
- Most useful single change: Check your skin periodically and ask someone to check your back.
- Commonest mistake: Waiting to see whether a changing lesion settles.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Melanoma found early is usually curable by simple excision, and found late it is not, which makes recognition the whole game.
The numbers, in one place
| Measure | Figure |
|---|---|
| ABCDE | Asymmetry, Border, Colour, Diameter, Evolving |
| Most important single feature | change over weeks or months |
| Non-melanoma signs | a sore that does not heal in 4 weeks, a scaly or pearly patch |
| Highest risk | fair skin, many moles, sunburn history, family history |
What helps
- Check your skin periodically and ask someone to check your back
- Photograph anything you are unsure about to compare later
- See a GP about change rather than appearance alone
- Protect skin from UV; prevention remains the largest lever
What to avoid
- Waiting to see whether a changing lesion settles
- Assuming a lesion is fine because it does not hurt
- Relying on apps to decide whether a mole needs checking
Where to go next
- Skin Cancer Signs: Common Questions Answered
- Skin Cancer Signs: The Quick Reference
- Dry Skin: Sorting the Evidence From the Noise
- Wound Care: What the Evidence Actually Says
When to get help
See a GP promptly about any mole that is changing in size, shape or colour, has an irregular or blurred edge, contains more than one colour, is larger than 6mm, or is itching, bleeding, crusting or inflamed. Also report any sore, lump or scaly patch that has not healed within four weeks.
Where this comes from
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.