Moles are common growths on the skin, appearing as small, pigmented spots. While most moles are harmless, some display unusual characteristics that warrant closer attention. These are known as atypical moles, or dysplastic nevi. Although these moles can appear concerning due to their irregular features, the vast majority of atypical moles are benign, meaning they are not cancerous.
Understanding Atypical Moles
Atypical moles have specific features that distinguish them from common moles. They often exhibit an irregular shape, where one half does not mirror the other. Their borders tend to be uneven, notched, or poorly defined, contrasting with the smooth, round edges of typical moles.
Coloration within atypical moles can also be varied, displaying multiple shades of tan, brown, black, or even pink and red. They are generally larger than common moles. These moles can appear anywhere on the body, though they are frequently found on the trunk, arms, legs, head, and neck.
The Risk of Cancer
A single atypical mole rarely turns into melanoma, the most serious form of skin cancer. The risk of an individual atypical mole becoming cancerous is very low, estimated to be about 1%. Most atypical moles remain stable throughout a person’s life and do not progress to malignancy.
Despite their benign nature, the presence of atypical moles signals an increased risk for developing melanoma elsewhere on the skin. Individuals with 10 or more atypical moles have a melanoma risk 12 times higher than the general population; having five or more also elevates this risk. This is because atypical moles serve as markers for an individual’s overall predisposition to melanoma, rather than being inherently cancerous themselves.
Most melanomas, approximately 70% to 80%, arise from previously normal-looking skin, not from existing moles. Only about 20% to 30% develop from pre-existing moles. In rare cases, Dysplastic Nevus Syndrome (FAMMM syndrome) involves a large number of atypical moles and a family history of melanoma, significantly increasing risk.
Recognizing Changes in Moles
Monitoring moles for any changes is an important step in early detection of melanoma. The “ABCDEs” of melanoma detection provide a useful guide for self-examination.
Asymmetry: One half of the mole does not match the other.
Border irregularity: Edges are uneven, scalloped, or poorly defined.
Color variation: Different shades of tan, brown, black, white, red, or blue.
Diameter: Larger than 6 millimeters (pencil eraser size), though melanomas can be smaller.
Evolving: Any change in size, shape, color, elevation, or new symptoms like itching, tenderness, bleeding, or crusting.
Regular self-checks, ideally monthly, allow individuals to become familiar with their skin and identify any new or changing spots.
Monitoring and Medical Consultation
For individuals with atypical moles, regular professional skin examinations by a dermatologist are advisable. The frequency of these examinations can vary based on an individual’s risk factors, often ranging from every few months to annually. During these visits, a dermatologist will carefully inspect all moles, often using a dermatoscope, a magnifying device for detailed mole inspection.
If a mole exhibits suspicious features, a biopsy may be recommended to determine if cancerous cells are present. An excision biopsy, which removes the entire mole, is often preferred for accurate diagnosis. For those with numerous moles or a history of atypical moles, photographic mole mapping (total body photography) is useful. This process creates a baseline record of all moles, enabling dermatologists to track subtle changes over time and detect new or evolving lesions. Medical consultation is important for accurate diagnosis and management of atypical moles.