Quick answer
What could mole changes mean?
Most moles are harmless, but a changing mole can be a sign of melanoma — the most serious type of skin cancer. See a GP urgently for a mole that changes shape, colour, size or bleeds, or looks different from your other moles. The ABCDE guide helps identify concerning features. Melanoma is highly treatable when caught early.
Know your skin — and report changes
Most moles (naevi) are harmless collections of pigment cells. Many people have dozens. However, melanoma — the most dangerous form of skin cancer — often starts as a new mole or a change in an existing one. Melanoma is highly curable when caught early — which is why knowing warning signs and seeing a GP promptly matters.
The UK diagnoses about 16,000 melanomas a year, and rates are rising — partly due to sun exposure and better detection.
The ABCDE guide
Use ABCDE to identify moles that need assessment:
A — Asymmetry. One half looks different from the other. Benign moles are usually symmetrical.
B — Border. Irregular, blurred, or jagged edges rather than a smooth, clear outline.
C — Colour. Uneven colour with multiple shades — brown, black, tan, red, white, or blue within one mole. Benign moles are usually one uniform colour.
D — Diameter. Larger than 6mm (pencil eraser size) — though melanomas can be smaller than this, so do not ignore small suspicious moles.
E — Evolving. Any change in size, shape, colour, elevation, or new symptoms — bleeding, itching, crusting.
Other warning signs
See a GP for:
- a new mole appearing after age 30
- a mole that looks different from your others (“ugly duckling” sign)
- a mole that bleeds without injury
- persistent itching in one mole
- a dark streak under a fingernail or toenail (acral melanoma)
- a sore that does not heal within 4 weeks
- a new skin lesion that grows quickly
Who is at higher risk
- fair skin that burns easily and tans poorly
- history of sunburn, especially blistering sunburn in childhood
- many moles — more than 100
- atypical moles — large, irregular moles
- family history of melanoma
- sunbed use — significantly increases melanoma risk
- weakened immune system — organ transplant recipients, immunosuppression
Melanoma can occur on any skin type, including dark skin — though it is less common. It may appear on palms, soles, and under nails in darker skin tones.
Checking your skin
- examine skin monthly — including back (use a mirror or partner), scalp, between toes, soles of feet, and genital area
- note existing moles with photos to track change over time
- report any new or changing lesion — do not watch and wait for months
What a GP will do
A GP examines the mole — often with a dermatoscope (magnified light). They may:
- reassure if clearly benign
- refer to dermatology on a urgent suspected cancer pathway if concerned
- photograph and monitor if uncertain but low suspicion
Suspicious moles are removed by excision biopsy — cut out with a margin of normal skin — and examined under a microscope.
If melanoma is diagnosed
Treatment depends on thickness (Breslow depth) and whether it has spread:
- thin melanoma — excision alone is usually curative
- thicker melanoma — may need wider excision, sentinel lymph node biopsy, immunotherapy, or targeted therapy
Early melanoma (stage 1) has over 95% five-year survival. Delayed diagnosis worsens prognosis.
Other skin cancers
Not all skin cancer is melanoma:
Basal cell carcinoma (BCC) — most common; pearly nodule, may ulcerate; grows slowly; rarely spreads.
Squamous cell carcinoma (SCC) — scaly or crusted growth; can spread if untreated.
Both need treatment but are less aggressive than melanoma. Any persistent non-healing skin lesion needs GP assessment.
Sun protection
- SPF 30+ sunscreen — apply generously, reapply every 2 hours
- seek shade 11am to 3pm in summer
- cover up — hat, sunglasses, long sleeves
- never use sunbeds
- protect children — sunburn in childhood increases melanoma risk
Sun protection reduces all skin cancer types.
Do not rely on apps alone
Mole-checking phone apps can help awareness but do not replace GP assessment of concerning lesions. If worried, see a GP — dermatology referral is appropriate.
When in doubt, check it out
Embarrassment or minimisation (“it’s probably nothing”) delays melanoma diagnosis. GPs would rather reassure you about a benign mole than miss an early melanoma. Two-week wait referral exists for suspicious skin lesions — use it.
Common questions
- What is the ABCDE guide for moles?
- Asymmetry (two halves look different), Border (irregular or blurred edges), Colour (uneven with multiple shades), Diameter (larger than 6mm, though melanomas can be smaller), Evolving (changing in size, shape or colour). Any one feature warrants assessment.
- What does melanoma look like?
- A new mole or change in an existing mole — often brown or black but can be pink, red, or skin-coloured. May be flat or raised, with irregular shape, uneven colour, and may bleed, itch, or crust. Can appear anywhere on the body, including areas not exposed to sun.
- Are all changing moles cancer?
- No — moles can change benignly with age. But any change should be assessed because melanoma can mimic benign moles. A GP or dermatologist uses a dermatoscope to examine moles closely.
- How can I reduce skin cancer risk?
- Avoid sunburn — use SPF 30+ sunscreen, seek shade 11am to 3pm, cover up, never use sunbeds. Check skin regularly including back, scalp, and soles of feet. Report new or changing lesions promptly.
- What happens if a mole is suspicious?
- A GP or dermatologist examines with a dermatoscope. Suspicious moles are removed surgically (excision biopsy) and examined under a microscope. If melanoma is confirmed, further treatment depends on thickness and stage — early melanoma is usually cured by excision alone.