Moles, medically known as nevi, are common skin growths that appear as small, often dark brown spots. These common skin features are generally harmless, with most individuals developing between 10 and 45 moles during their lifetime. While their presence is widespread, understanding their formation and significance is important for skin health.
How Moles Form
Moles develop when pigment-producing cells, called melanocytes, grow in clusters rather than being evenly distributed throughout the skin. Melanocytes are responsible for producing melanin, the natural pigment that gives skin, hair, and eyes their color, creating a denser, more visible spot.
Mole formation is influenced by genetic factors and environmental exposure. Some individuals are genetically predisposed to developing more moles, a tendency often inherited within families. Additionally, exposure to ultraviolet (UV) radiation from the sun plays a significant role, particularly for those with fair skin. Hormonal changes, such as during puberty or pregnancy, can also lead to moles becoming darker or larger.
Do Moles Have a Biological Purpose?
From a biological standpoint, moles do not serve a known functional purpose for the human body. They are simply benign aggregations of melanocytes. Unlike other specialized cells that perform specific physiological roles, moles are non-functional growths. They represent a localized proliferation of cells that are benign, meaning they are not cancerous.
These collections of pigment cells typically pose no threat and are a common characteristic of human skin. While some moles are present at birth, many appear during childhood and adolescence. Over time, moles can change in appearance, becoming lighter, more raised, or even fading away completely.
What Moles Can Indicate
While moles do not have a biological purpose, they hold significance as unique identifying marks for individuals and also as indicators of skin health, particularly concerning the potential for melanoma, a serious form of skin cancer. Monitoring changes in existing moles or the appearance of new ones is an important aspect of early detection.
Healthcare providers often recommend using the “ABCDEs” rule to help identify suspicious moles:
- Asymmetry: One half of the mole does not match the other.
- Borders: Irregular, notched, blurred, or ragged.
- Color: Multiple colors or uneven distribution of color within the mole.
- Diameter: Larger than about 6 millimeters (the size of a pencil eraser).
- Evolving: Any change in size, shape, color, or height, or the development of new symptoms like itching or bleeding.
Regular self-checks, ideally every one to two months, are advised to note any such changes. It is also important to seek professional evaluation for any mole that looks different from others on the body, sometimes referred to as the “ugly duckling” sign. Consulting a dermatologist for any concerning changes or new growths allows for timely assessment and intervention.