Moles, medically known as nevi, are common skin growths formed from clusters of melanocytes, the pigment-producing cells in the skin. While most moles are benign, they can change over time. Understanding these changes, particularly in their growth patterns, helps distinguish between typical development and potentially concerning signs.
Normal Growth Patterns of Moles
Moles typically emerge and evolve throughout childhood and adolescence, with most individuals developing the majority of their moles during the first two decades of life, with peak appearance often coinciding with puberty. Moles present at birth, known as congenital nevi, are less common than acquired moles that develop later. As a child grows, their moles may increase in size, darken, or lighten, and some can even fade or disappear entirely over many years. By adulthood, it is common to have between 10 to 40 moles, though this number can vary. New moles can continue to appear into a person’s 30s or early 40s.
Factors Influencing Mole Development
Mole formation and changes are influenced by genetic and environmental factors. Genetic predisposition plays a significant role, as family history can impact the number and types of moles an individual develops. Specific gene variants can affect melanin production and increase mole count. Sun exposure, particularly intense and intermittent exposure, is another factor that stimulates melanocytes and can lead to new moles or changes in existing ones. Hormonal fluctuations, such as those occurring during puberty and pregnancy, can also cause moles to darken or temporarily increase in size due to heightened melanin activity.
Identifying Concerning Mole Changes
While moles can normally change, certain characteristics signal a need for closer evaluation. Rapid or noticeable changes in a mole’s appearance are particularly concerning. Healthcare professionals use the ABCDE mnemonic to identify potential signs of melanoma, a serious form of skin cancer:
Asymmetry: One half of the mole does not match the other.
Border irregularity: Edges are uneven, notched, or blurred.
Color variation: Multiple shades of brown, black, tan, red, white, or blue within the same mole.
Diameter: Often larger than 6 millimeters (pencil eraser size), though they can be smaller.
Evolving: Any change in size, shape, color, or elevation over time, the most important sign.
New symptoms such as itching, bleeding, oozing, crusting, or tenderness of a mole warrant immediate attention. A mole that looks distinctly different from others on the body, sometimes called the “ugly duckling” sign, is another important warning.
When to Consult a Healthcare Professional
Regular self-skin exams are recommended monthly to monitor existing and detect new moles, using full-length and hand mirrors to examine all body areas, including less visible spots. If any ABCDE signs are observed, or if a mole becomes itchy, bleeds, or changes in sensation, a medical evaluation is necessary. A dermatologist can assess moles using a dermatoscope, a magnifying tool providing a detailed view of skin structures. If a mole appears suspicious, a biopsy may be performed for microscopic examination, with common techniques including shave, punch, or excisional biopsies. Early detection of melanoma significantly increases the chances of successful treatment.