The ABCDE checklist (see below) has been developed to help differentiate between a normal mole, a seborrhoeic keratosis and a melanoma.

• Normal moles are usually round or oval, with a smooth edge, and no more than 6mm (1/4 inch) in diameter
• Seborrhoeic keratoses (also known as seborrhoeic warts, basal cell papillomas, senile keratoses) are very common, harmless growths on the skin. They are much more common than skin cancers. Seborrhoeic keratoses are often pigmented (pink, light/dark brown) and usually have a characteristic ‘stuck on’ appearance.

A dark seborrhoeic keratosis can look similar to a melanoma. Seborrhoeic keratoses are not infectious and do not become malignant. Once present, they usually stay, and new ones often appear over the years. They are usually not treated although they can be removed if they are troublesome (e.g. catching on clothing).