A mole (nevus) is a common skin growth formed when pigment-producing cells (melanocytes) grow in clusters. Moles can appear anywhere on the body, varying widely in size, shape, and color. Most people have moles, and the vast majority are harmless. Understanding the different classifications is important for recognizing changes that may require medical attention.
Acquired (Common) Moles
Acquired moles are the most prevalent type, developing after birth, typically during childhood and young adulthood. The average adult often has between 10 to 40 of these common moles. They are defined by a uniform appearance, generally measuring less than 6 millimeters in diameter (about the size of a pencil eraser).
These moles are usually round or oval-shaped with clear, distinct borders. Their color is typically consistent, ranging from light tan to dark brown or pink. They often start as flat spots and may become slightly raised or dome-shaped over time.
Congenital Moles (Nevi Present at Birth)
Congenital nevi are moles present at birth or appearing within the first few months of life, occurring in about 1% to 2% of the population. They result from an overgrowth of melanocytes during fetal development and commonly appear on the trunk or limbs.
Their appearance varies significantly, ranging from light to dark brown, and they may grow thick, dark hair. While most are small, some can be quite large. Larger congenital nevi (giant congenital melanocytic nevi) carry a slightly increased risk of developing into melanoma, requiring close monitoring.
Atypical (Dysplastic) Moles
Atypical moles (dysplastic nevi) are benign growths that differ from common moles. They are sometimes described as having a “fried-egg” appearance, featuring a darker raised center surrounded by a flatter, lighter area. These moles often exceed 6 millimeters in diameter and feature irregular, non-round shapes.
The coloration is often varied, displaying a mix of shades like tan, dark brown, pink, or red. While they are not cancerous, having a high number of atypical moles is a risk factor for developing melanoma. Individuals with 10 or more atypical moles are at a significantly higher risk compared to the general population.
Recognizing Dangerous Changes (The ABCDE Method)
The ABCDE method is a standardized tool used to monitor moles and detect early warning signs of melanoma. This method focuses on five specific characteristics, any change in which warrants professional evaluation by a dermatologist.
A stands for Asymmetry, meaning the two halves of the mole would not match if a line were drawn through it. Common, benign moles are typically symmetrical. B represents Border irregularity, referring to edges that are blurred, notched, or ragged, unlike the smooth borders of a normal mole.
C is for Color variation, indicating multiple colors or shades within the mole, such as black, brown, red, white, or blue. Common moles usually have a single, consistent color. D denotes Diameter; a mole larger than 6 millimeters (the size of a pencil eraser) should be viewed with suspicion.
E is for Evolving, referring to any change over time in a mole’s size, shape, color, or elevation. New symptoms like bleeding, itching, or tenderness are also considered part of the evolving criterion. Paying close attention to any mole that is changing rapidly is the most effective way to catch potential skin cancer in its earliest, most treatable stage.