Moles (naevus or nevi) are raised or flat forms of pigmented skin, usually appearing within the first 20 years of a person’s life, according to the American Academy of Dermatology. They can show up anywhere on the body in different shapes, sizes and colors. Some are potentially dangerous. See a dermatologist if a mole’s appearance changes.

Congenital Naevus

Congenital moles are brown or black spots that we are born with or develop within the first few months after birth. They are often called birthmarks. They’re usually round or oval, but the shape and size can vary. A “small” congenital mole is one less than 1.5 cm in diameter. A “medium” congenital mole is up to 10 cm in diameter. A “large” congenital mole is anything over 10 cm in diameter. These moles usually appear on the lower body. A congenital mole located on the neck, head or spine can be cause for concern because it may mean a higher likelihood for seizures.

Acquired Naevus

An acquired mole is one that grows after birth or at any age. They can be a variety of colors from light pinks, tans, brown, dark brown or black. Darker acquired moles usually are found on darker skin tones. Acquired naevus can be raised, flat, rounded or rigid. All acquired moles should be watched closely, especially if they pop up after puberty, for signs of skin cancer.

Dysplastic Naevi

Dysplastic moles are a type of acquired mole, because they don’t show up until puberty or later. They are often called “atypical” moles because they are not round. But a simple atypical mole is not always dysplastic. For example, a dysplastic mole will often bridge together with another dysplastic mole, while a normal atypical mole will not. Dysplastic moles are shaped wavy or rigid and are usually flat. They are usually small and brown. Because they are one of the most concerning moles in regard to skin cancer, see a dermotologist if one changes or grows.


Freckles are another type of acquired mole, but we often don’t think of them as moles. Freckles are spots on the skin formed with pigmented skin cells. One freckle by itself looks very similar to a traditional mole. They tend to fade during the winter because melanin isn’t produced as much during the winter months. Sun spots are a type of freckle that are also called age spots. They tend to last longer than freckles and don’t fade as much during the winter. A freckle or sun spot can turn into skin cancer, so watch for raising, irregular shape changes or color changes.

Halo Naevi

A halo mole is another type of acquired mole. It has a white ring surrounding it. They are not uncommon and tend to develop in childhood and early adulthood. The white ring may be the body’s way of attacking the mole. Halo moles are no more dangerous than other moles. However, the white ring is more susceptible to sunburn.