A mole is a common benign growth on the skin. These spots form when melanocytes, the cells responsible for producing skin pigment, grow in clusters. Most individuals develop between 10 and 40 moles throughout their lives, with many appearing during childhood and adolescence. While generally harmless, understanding why new moles appear and what characteristics might signal concern is important for skin health.
Why Moles Appear
Moles form when melanocytes, the specialized cells that produce melanin, gather in a concentrated area of the skin. This clustering creates the visible pigmented spots. Several factors influence the development of new moles.
Genetic predisposition plays a role, as individuals often inherit a tendency to develop a certain number and pattern of moles. Certain gene variants can influence melanin production and increase mole density, particularly in those with fair skin and light hair. Environmental factors, especially sun exposure, also contribute significantly. Ultraviolet (UV) radiation stimulates melanocytes, potentially triggering the formation of new moles or darkening existing ones.
Hormonal fluctuations throughout life can further influence mole appearance and changes. Periods such as puberty, pregnancy, and even menopause can lead to existing moles becoming darker, larger, or more numerous due to increased levels of melanocyte-stimulating hormone (MSH). While new moles can appear at any age, they are less common in elderly individuals, and any new mole appearing later in life warrants evaluation.
Exploring Common Mole Types
Common acquired nevi are among the most frequently observed moles, typically appearing after birth and often during childhood or adolescence. These moles are usually small, generally less than 5 millimeters in diameter, with a smooth surface and a uniform color, ranging from tan to dark brown. They tend to be round or oval with well-defined, smooth borders.
Another type is the congenital nevus, which is present at birth or develops within the first year of life, affecting about 1% to 2% of the population. These moles can vary in size, shape, and color. While most are benign, a small percentage, especially larger ones, carry a slightly increased risk of developing into melanoma later in life.
Atypical nevi, also known as dysplastic nevi, represent another category. These moles are benign but often have features that can resemble melanoma, such as irregular shapes, indistinct borders, and multiple colors. People with atypical nevi have a higher risk of developing melanoma, particularly if they have many such moles or a family history of them.
Recognizing Concerning Moles
When a mole suddenly appears or changes, it is helpful to use the “ABCDE” rule as a guide to identify potentially problematic moles that warrant professional evaluation.
- Asymmetry: One half of the mole does not match the other half if an imaginary line were drawn through its center. Benign moles are typically symmetrical.
- Border irregularity: The edges of the mole are ragged, notched, blurred, or poorly defined, contrasting with the smooth, even borders of most harmless moles.
- Color variation: The mole displays multiple shades of brown, black, tan, red, white, or even blue within the same lesion. A uniform color is generally a reassuring sign.
- Diameter: Moles larger than 6 millimeters (about the size of a pencil eraser) are of greater concern, though melanomas can sometimes be smaller.
- Evolving: Any change in the mole’s size, shape, color, elevation, or if it starts to itch, bleed, or crust, should prompt immediate medical attention.
If any of these “ABCDE” characteristics are present, or if a mole simply looks different from others on your body, it is advisable to consult a dermatologist for a thorough examination.