In most patients, the melanoma skin cancer develop on a clinically normal skin. Since most people do not develop new melanocytic nevi in adulthood, if such an eventuality arise, the patient should immediately consult his dermatologist for clinical evaluation of the new nevus.

In other patients melanomas originate from pre-existent nevi that change their shape or color. In these cases it’s important for the patient to be aware of these changes and refer without delay to his doctor.

Early signs or symptoms of the melanoma skin cancer are changes to the shape, color, size; bleeding or itching of existing nevi or, in the case of nodular melanoma, the appearance of new lesions anywhere on the skin.

These early symptoms are summarized by the mnemonic ABCDE rule (on the left side of the images are shown the melanomas, on the right side the normal moles):

• Asymmetry: the skin lesion is asymmetric.

• Borders: the lesion’s border is irregular.

• Color: melanomas usually have multiple variegated colors.

• Diameter: nevi with a diameter greater than 6 mm (0.236 inch) are more likely to be melanomas.

• Enlarging or evolving over time.

Recently has been proposed a revision of the ABCDE rule, called ABCDEFG, with the aim of early identification of some types of aggressive and dangerous melanoma such as the nodular melanoma. In the ABCDEFG rule, the last letters have the following meaning:

• Elevated: the lesion is elevated above the skin surface.

• Firm: it is firm to the touch.

• Growing: it has grown rapidly in a short time, a few months or weeks.

The visual diagnosis is still the most common method used by health professionals to detect melanomas. Therefore, it is recommended to learn what a melanoma skin cancer looks like, to be aware of nevi, checking them for changes and to show any suspicious moles or lesions as soon as possible to a doctor with skills in this field.