The short answer
A mole or skin spot that changes in size, shape, or color, or a sore that does not heal, can be a sign of skin cancer, including melanoma. The ABCDE rule helps spot warning signs to bring to a doctor.
A mole that changes in size, shape, or color can be a warning sign of skin cancer.
The ABCDE rule helps: Asymmetry, Border, Color, Diameter, and Evolving.
A new growth or a sore that does not heal can also be a sign of skin cancer.
Melanoma is the most serious skin cancer and is very treatable when found early.
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The full explanation.
The simple version
Most moles are harmless. But a mole or skin spot that changes over time — in size, shape, or color — or a sore that does not heal can be a warning sign of skin cancer, including melanoma. The good news is that skin cancer found early is very treatable.
The ABCDE rule
A simple way to spot warning signs in a mole:
- A — Asymmetry: one half does not match the other
- B — Border: edges are ragged or irregular
- C — Color: more than one shade, or uneven color
- D — Diameter: larger than a pencil eraser (about 6 mm)
- E — Evolving: changing in size, shape, or color over time
Other skin warning signs
A new growth, a sore that does not heal, or a spot that itches, bleeds, or crusts can also be signs of skin cancer. A spot that stands out as different from your other moles is worth checking.
A mole that is changing or a sore that will not heal should be checked.
When to see a doctor
See a doctor or dermatologist for any mole or skin spot that is changing, looks unusual, or does not heal. Early melanoma is very treatable, so it is worth getting new or changing spots checked.
Words to know
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Common questions
▸What changes in a mole should I watch for?
Watch for a mole that changes in size, shape, or color, or one that looks different from your others. A helpful guide is the ABCDE rule: Asymmetry, an irregular Border, uneven Color, a large Diameter, and Evolving or changing over time.
▸What is the ABCDE rule?
It is a simple checklist for moles: Asymmetry (one half unlike the other), Border (irregular edges), Color (more than one shade), Diameter (larger than a pencil eraser), and Evolving (changing over time).
▸What else signals skin cancer?
A new growth, a sore that does not heal, or a spot that itches, bleeds, or crusts can be signs of skin cancer, including basal or squamous cell cancers.
▸When should I see a doctor?
See a doctor or dermatologist for any mole or skin spot that is changing, looks unusual, or does not heal. Melanoma is very treatable when caught early.
Questions to ask your doctor
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