Atypical moles, also known as dysplastic nevi, are common dermatological features, with approximately one in ten Americans having at least one atypical mole. These moles differ from regular moles in several ways: they are often larger, irregular in shape, and may exhibit a variation in color, ranging from tan to dark brown shades on a pink or skin-toned background. They may have uneven borders, including notches, and may blend into the surrounding skin with a flat portion that aligns with the skin surface. These characteristics can mimic the appearance of melanoma, a potentially fatal form of skin cancer, raising concerns about the risk of progression from atypical moles to melanoma.

Risk of Melanoma in Individuals with Atypical Moles

While atypical moles are considered precancerous lesions—suggesting a higher likelihood of transforming into melanoma than typical moles—most atypical moles do not become malignant. Melanoma, which affects approximately 40,000 individuals in the United States annually, is known to develop from both atypical and normal skin. In fact, studies show that half of individuals diagnosed with melanoma have numerous atypical moles. However, it is important to note that the vast majority of moles, whether atypical or typical, remain benign throughout a person’s life.

The risk of melanoma is especially pronounced in individuals with fair skin and heavy freckling, which are indicators of past sun exposure, a significant environmental risk factor for melanoma. While having atypical moles increases the likelihood of developing melanoma, it does not guarantee progression. Most melanomas arise de novo, meaning they develop in previously normal skin rather than from pre-existing benign moles.

Clinical Implications and Risk Assessment

Individuals with a family history of melanoma or multiple atypical moles should undergo regular dermatologic surveillance, as they are at heightened risk. Family members of patients with familial atypical multiple mole melanoma syndrome (FAMMM) are particularly vulnerable. In such families, the risk of melanoma is substantially higher, with individuals possessing multiple atypical moles having a 14-fold increased risk compared to the general population. Conversely, individuals with only a single atypical mole face a twofold increased risk of developing melanoma.

In cases where multiple atypical moles are present, especially when several family members are affected by melanoma, close monitoring is crucial. However, despite concerns, removing all atypical moles does not necessarily reduce the lifetime risk of developing melanoma. This is due to the fact that melanomas typically arise de novo and not from pre-existing moles. As a result, the decision to remove moles should be carefully considered based on clinical risk and personal history.

Management and Surveillance

Physicians primarily diagnose atypical moles through physical examination, but confirmation often requires a biopsy. Biopsies are typically performed using local anesthesia in the doctor’s office. A pathologist examines the removed tissue under a microscope to confirm whether the mole is benign or malignant. Pathological features such as “severely dysplastic” or “atypical melanocytic hyperplasia” suggest a concern for melanoma, although a definitive diagnosis may not be immediately possible. In cases where the diagnosis is unclear, doctors often recommend removing the mole with a margin of clinically normal skin to ensure complete excision.

The management of atypical moles depends on the degree of dysplasia:

• Mild dysplasia: Moles with mild dysplasia may be monitored through regular follow-ups rather than being immediately excised.
• Moderate dysplasia: Moles exhibiting moderate dysplasia may also require removal, especially if the initial biopsy did not capture the full lesion.
• Severely dysplastic moles: These moles are typically excised with a margin of about 0.5 cm (approximately a quarter inch) of normal skin to reduce the risk of melanoma.

Self-Examination and Regular Checkups

As part of comprehensive melanoma prevention, individuals should perform monthly skin self-examinations to detect changes in moles. Just as women who conduct regular breast self-exams have a higher chance of detecting breast cancer early, monthly skin checks can significantly improve early melanoma detection and cure rates. Any mole that changes in size, shape, or color—or begins to itch, bleed, or ulcerate—should be biopsied promptly.

Conclusion

Atypical moles are common and serve as an important marker for melanoma risk. Although they are considered precancerous, not all atypical moles will develop into melanoma, and most moles, whether atypical or typical, remain benign. Risk is elevated in individuals with multiple atypical moles, especially in those with a family history of melanoma. Regular dermatologic surveillance, including self-exams and professional evaluations, is essential for early detection of melanoma, particularly for those at increased risk. While the removal of atypical moles may be warranted in some cases, most melanomas arise de novo, meaning prevention strategies should focus on reducing sun exposure and ensuring diligent monitoring for new or changing lesions.

References

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