A mole is referred to as a nevus , or the plural form nevi , in medical literature. This describes normal and benign skin growths. Moles occur as a result of increased pigmentation in the skin. This may be due to increased production of melanin (pigment), an increased number of pigment-producing cells (melanocytes/nevus cells) or a combination of these.
The vast majority of moles appear in the first 30-40 years of life (acquired mole). Especially during puberty, many new moles appear. Around the age of 40, a person has an average of 25-30 moles. Afterwards, many find that the number decreases somewhat. Only a small number of moles are congenital.
Moles are most common among people with fair skin and eyes. Heredity also plays a role. Moles can appear on any part of the body. However, they are most common in areas exposed to the sun.
It is not unusual for a mole to change throughout its life. Some can grow and over time protrude slightly from the skin. Others may change colour, preferably by becoming somewhat lighter with age. Pregnant women also experience a number of mole changes. Changing moles, especially at a young age, is thus a normal phenomenon and only exceptionally a sign of melanoma.
There are other pigment changes that may resemble moles, but are structurally different. Examples of this are freckles (ephelides). In freckles, the number of pigment cells is normal or reduced, but there is increased pigmentation in the skin cells (keratinocytes). Freckles darken with sun exposure and fade with a lack of sun, as many experience depending on the seasons.
There are different types of acquired moles depending on where in the skin the pigment cells are located, including: junctional, dermal and compound.
Junctional moles are seen as fairly symmetrical, small, deeply pigmented and flat skin changes. This is a very common type of mole where the pigment cells sit high in the skin.
A dermal mole is often seen as a more prominent skin change with varying degrees of pigmentation, for example pink, skin colored or light brown. The surface can be either smooth or rough. In such moles, the pigment cells are located somewhat deeper in the skin.
A compound mole is probably an intermediate stage from junctional to dermal mole. Such moles therefore have a mixed appearance; preferably with a slightly protruding, lighter skin change (dermal component) centrally and with a flat and darker skin change (junctional component) behind/around.
These are moles that can partly resemble mole cancer (melanoma mole cancer), but are considered benign skin changes. They occur on both sun-exposed and non-sun-exposed areas and do not disappear with age. The diagnosis is made based on microscopic examination. Dysplastic/atypical moles are often 5 mm or larger, and they may have a somewhat irregular shape and demarcation. People who have many such moles possibly have a somewhat higher risk of developing mole cancer compared to the general population.
Halo mole, most often referred to as halonevus, is a mole surrounded by a light ring. This white ring occurs because the body's immune system attacks the pigment cells in the mole. In the long run, it may disappear completely. This is a fairly common and harmless phenomenon, especially during puberty. If, on the other hand, you develop many of these in a short time, and especially as an adult, it is a warning sign in relation to cancer.
Congenital moles are present at birth or develop during the first few months of life. They are often larger in size, and are often seen as hairy and/or wart-like. Congenital moles are classified according to diameter at birth, with some (depending on location and size) requiring specialist follow-up. Large congenital moles larger than 20 cm in adulthood are referred to as "giant moles".
Here we have mentioned a selection of mole types, but there are far more. Examples of other mole types are blue nevus, Spitz nevus, Reed nevus and nevus spilus. If you are unsure about a mole, it is recommended to see a doctor.
