The ABCDE Rule for Melanoma: What to Look For
Why the ABCDE rule matters
Melanoma is one of the most serious forms of skin cancer, but it is also one of the most treatable when caught early. The ABCDE rule was developed by dermatologists as a simple, memorable framework to help people recognise the warning signs of melanoma during regular skin self-checks.
No single feature alone confirms melanoma, and not every melanoma displays all five features. The ABCDE rule is a screening tool to help you decide when a mole or lesion needs professional review — it does not replace a dermatologist's assessment.
Common misconceptions
- "Melanoma only appears in sun-exposed areas." It can develop anywhere, including the scalp, soles of the feet, palms, and under nails.
- "If a mole doesn't tick every ABCDE box, it's safe." Even one feature, especially evolution (change), warrants review.
- "Only large moles are dangerous." Some melanomas are smaller than 6mm at diagnosis, particularly when detected early.
- "Melanoma always looks dark or black." Amelanotic melanomas can appear pink, red, or skin-coloured with little pigment.
The ABCDE criteria
- A — Asymmetry: One half of the lesion doesn't match the other
- B — Border: Edges are irregular, ragged, notched, or blurred
- C — Colour: Variation in colour (browns, blacks, reds, whites, blues within one lesion)
- D — Diameter: Larger than 6mm (about the size of a pencil eraser), though melanomas can be smaller
- E — Evolution: Any change in size, shape, colour, or new symptom (bleeding, crusting, itching)
For a broader checklist of skin changes to monitor, see our guide on what to track with skin concerns.
The 'ugly duckling' sign
Dermatologists also use the "ugly duckling" concept: most moles on a person's body tend to resemble each other, so a mole that looks noticeably different from its neighbours deserves closer attention, even if it doesn't meet all the ABCDE criteria.
When to seek medical care
Seek urgent dermatology review if a mole:
- Is bleeding, ulcerating, or rapidly growing
- Has changed significantly in the past weeks to months
- Is new and growing in someone over 40, especially with an irregular appearance
Book a routine dermatology appointment if:
- A mole shows one or more ABCDE features but is stable and not rapidly changing
- You have many moles and want a baseline mole-mapping assessment
Routine self-monitoring is appropriate for:
- Stable, symmetrical moles with regular borders and consistent colour that haven't changed over time
How to check your skin
- Check in good lighting with a full-length mirror; use a hand mirror for hard-to-see areas
- Include scalp, between toes, palms, and soles
- Monthly self-checks; annual review with your GP or dermatologist
- Photograph moles to track changes over time
If you are unsure whether a rash-like change is a lesion or an inflammatory skin condition, eczema vs psoriasis may provide useful context.
Related Skin Guides
Explore related skin guides to better understand common skin changes, warning signs, and when further review may be needed.
- Skin Concerns: What to Track and When to Get Checked
- Eczema vs Psoriasis: Key Differences Explained
- Acne: Causes, Triggers, and Evidence-Based Management
Skin concerns are often easier to understand when looked at alongside pattern, appearance, and change over time. You can explore related guides above or use Healio360's skin assessment tool for more structured guidance.
