Prevention
Melanoma Warning Signs: What to Look For and When to Act
The ABCDE rule, the ugly-duckling sign, and the specific mole changes that warrant a same-week dermatologist visit.
Melanoma is the deadliest form of skin cancer, but it is also one of the most curable when caught early. Five-year survival is above 99 percent for localized disease and drops sharply once it spreads. Almost every melanoma is visible on the skin before it becomes dangerous, which is why self-exams and dermatologist visits matter so much.
This guide covers what dermatologists actually look for, the mole changes that should move you to the top of the schedule, and the ones that don't.
The ABCDE rule in practice
Asymmetry, Border irregularity, Color variation, Diameter over 6mm, and Evolution. Any one is worth showing a dermatologist. Evolution — change over weeks or months — is the strongest single signal.
Take phone photos of any mole you're watching. Compare monthly. The camera catches drift that memory misses.
The ugly duckling sign
Most people have their own mole 'pattern.' A lesion that looks meaningfully different from your other moles — darker, larger, or a different shape — is worth checking, even if it doesn't hit all five ABCDE criteria.
Melanoma on darker skin
Acral melanoma appears on palms, soles, under nails, and mucous membranes, and disproportionately affects Fitzpatrick V and VI. A dark streak under a nail that wasn't there last year is the classic presentation. Reggae legend Bob Marley died of acral melanoma diagnosed too late.
When to book same-week
- A mole that bleeds, itches, or crusts without trauma
- A rapidly growing pink or red bump
- A new pigmented streak under a fingernail or toenail
- Any mole that looks obviously different from your others
Key takeaways
- ABCDE plus the ugly-duckling rule catch most melanomas.
- Evolution over time is the strongest single sign.
- Darker skin: check palms, soles, and nail beds.