Moles are small, colored skin growths caused by overproduction of pigmented skin cells called melanocytes. They are typically flat or raised, may vary in color from light to dark brown, may be rough or smooth, and may be hairless or hairy. Less commonly, a mole may be a bluish-black color, may be surrounded by a ring of paler skin, or may be larger than normal and unevenly colored.
Moles may be present at birth, but most appear later, and almost all adults have several moles. Most moles are noncancerous, but occasionally they may develop into malignant melanoma. Warning signs in an existing mole include a change in shape or size, a change in color or uneven coloring, crustiness, itching, inflammation, ulceration, bleeding, and an irregular edge.
The sudden appearance of a new mole may also indicate melanoma. Any such changes should be reported to a doctor promptly. Most moles are harmless and do not need treatment, although they can be surgically removed for cosmetic reasons