The first sign of a melanoma is often a new mole or a change in the appearance of an existing mole.
Normal moles are usually round or oval, with a smooth edge, and no bigger than 6mm (1/4 inch) in diameter.
See your GP as soon as possible if you notice changes in a mole, freckle or patch of skin, particularly if the changes happen over a few weeks or months.
Signs to look out for include a mole that's:
- getting bigger
- changing shape
- changing colour
- bleeding or becoming crusty
- itchy or sore
Melanomas can appear anywhere on your body, but they most commonly appear on the back in men and on the legs in women. They can also develop underneath a nail, on the sole of the foot, in the mouth, or in the genital areas, but these types of melanoma are rare.
ABCDE of moles
Most moles are harmless, but in a few rare cases they can develop into an aggressive form of skin cancer called malignant melanoma.
The ABCDE checklist can help you tell the difference between a normal mole and a melanoma:
Melanomas are asymmetrical. They have two very different halves and are an irregular shape.
Melanomas have a notched or ragged border.
Melanomas will be a mix of two or more colours.
Melanomas are larger than 6mm (1/4 inch) in diameter.
E: Enlargement or elevation
A mole that changes size over time is more likely to be a melanoma. A melanoma usually gets bigger and is raised or elevated above the surface level of the skin.
Melanoma of the eye
In rare cases, melanoma can develop in the eye. It develops from pigment-producing cells called melanocytes.
Eye melanoma usually affects the eyeball. The most common type is uveal or choroidal melanoma, which occurs at the back of the eye. Very rarely it can occur on the conjunctiva (the thin layer of tissue that covers the front of the eye) or in the iris (the coloured part of the eye).
Noticing a dark spot or changes in vision can be signs of eye melanoma, although it's more likely to be diagnosed during a routine eye examination.
Content supplied by the NHS and adapted for Ireland by the HSE