A mole, medically known as a melanocytic nevus, is a common, non-cancerous skin growth resulting from a cluster of cells called melanocytes. These specialized cells produce melanin, the pigment that gives skin its color. Most people develop between 10 and 40 moles over their lifetime, primarily appearing before age 30. While they can be present at birth, the majority are acquired later and are generally uniform in appearance, ranging in color from tan to dark brown.
The Normal Growth Cycle of Benign Moles
Benign moles grow, often in response to natural physiological changes. Moles present at birth, known as congenital nevi, will grow proportionally as a child grows. The most significant period for the development and growth of acquired moles is during childhood and adolescence.
Hormonal fluctuations, such as during puberty or pregnancy, can stimulate melanocytes, causing moles to darken or slightly enlarge. As a person reaches adulthood, the growth of moles typically slows down and stabilizes. Some moles may even begin to fade, become raised, or lose their pigment as part of a normal aging process called senescence.
Different Types of Moles and Their Growth Patterns
The appearance and evolution of a benign mole depend on the specific layer of skin where the melanocytes are clustered. Moles are generally classified into three main types based on this depth. Junctional nevi are flat because their cells are located only at the junction between the epidermis (outer layer) and the dermis (inner layer).
Over time, the cells in a junctional nevus may migrate deeper into the dermis, transforming the mole into a compound nevus. This migration results in a mole that is slightly raised. If the cells move entirely into the dermis, the mole becomes a dermal nevus, presenting as a raised, often flesh-colored or pale bump. This progression from a flat spot to a raised nodule is a normal, expected form of growth.
Identifying Suspicious Mole Changes (The ABCDE Rule)
A rapid or irregular change in a mole’s appearance is the primary reason for concern. Dermatologists utilize the ABCDE rule to help identify the characteristics of potentially malignant transformation.
The ABCDE characteristics are:
- Asymmetry: One half of the mole does not match the other half if an imaginary line is drawn through the middle.
- Border: The edges are often irregular, appearing notched, scalloped, or poorly defined.
- Color: Variation is present, particularly if the mole contains multiple shades of brown, black, tan, or has areas of red, white, or blue.
- Diameter: The mole is usually greater than 6 millimeters, which is roughly the size of a pencil eraser.
- Evolving: There is any noticeable change in the mole’s size, shape, color, or elevation over a short period.
When to Consult a Dermatologist
Any mole that exhibits one or more of the ABCDE characteristics should be evaluated by a medical professional. A particularly concerning sign is a mole that looks distinctly different from all the other moles on your body, often referred to as the “ugly duckling” sign.
You should also seek evaluation if a mole develops new symptoms such as persistent itching, tenderness, bleeding, or if it forms a non-healing sore. Professional skin cancer screenings can detect issues early, significantly improving treatment outcomes.