Moles are common skin growths that can appear anywhere on the body. Medically known as nevi, these spots form when pigment-producing cells called melanocytes cluster together. Most individuals develop between 10 and 45 moles during childhood and adolescence. While typically small, moles can vary in color, shape, and size, and their appearance can change over time.
Understanding Moles and Sun Exposure
Moles are composed of melanocytes, cells responsible for producing melanin, the natural pigment that gives skin its color. When skin is exposed to ultraviolet (UV) radiation from the sun, melanocytes are stimulated to produce more melanin. This process is a natural defense mechanism. The increased melanin production can lead to existing moles becoming darker or more noticeable, similar to how the surrounding skin develops a tan. Sustained or cumulative sun exposure can also trigger changes in a mole’s appearance, and UV rays can encourage the development of new moles.
When Mole Changes Signal a Problem
While some darkening of moles due to sun exposure can be a normal occurrence, certain changes warrant prompt medical evaluation. It is important to distinguish between benign, expected changes and those that might indicate a more serious condition, such as melanoma, a type of skin cancer. Melanoma often arises from changes in an existing mole or as a new, unusual spot. Dermatologists use the “ABCDEs” rule as a guide to help identify potentially problematic moles.
The ABCDEs of Moles
Asymmetry: One half of the mole does not match the other half.
Border: Irregular, notched, or poorly defined edges.
Color: Multiple colors or an uneven distribution of shades like tan, brown, black, red, white, or blue.
Diameter: Larger than 6 millimeters, roughly the size of a pencil eraser.
Evolving: Any noticeable change in the mole’s size, shape, color, or elevation over time.
Additionally, new symptoms such as bleeding, itching, or crusting within a mole, or a sore that does not heal, require medical attention.
Sun Protection and Mole Monitoring
Protecting your skin from UV radiation is important for overall skin health and for monitoring moles. Apply broad-spectrum sunscreen with an SPF of 30 or higher, reapplying every two hours or more frequently after swimming or sweating. Seek shade, especially during peak sun hours (typically between 10 a.m. and 4 p.m.), and wear protective clothing such as lightweight, tightly woven fabrics, wide-brimmed hats, and sunglasses. Avoiding tanning beds is also recommended, as they emit harmful UV radiation.
Regular self-skin exams are important for recognizing any new or changing moles. For most adults, an annual professional skin check by a dermatologist is advisable. Individuals with a family history of skin cancer, a significant number of moles, or a personal history of skin cancer may benefit from more frequent checks, potentially every three to six months.