An atypical or dysplastic nevus is a non-cancerous mole that shares some features with melanoma, but is completely benign. While individual dysplastic nevi do not usually become melanomas, they may be markers for an increased risk of melanoma. Patients who are at a particularly increased risk are those who meet the criteria for Familial Atypical Nevus Syndrome. In Familial Atypical Nevus syndrome, patients have numerous moles (usually more than 50), some of which are atypical and a family history of melanoma.
Some of the features that atypical nevi share with melanomas are asymmetry, border irregularity, non-uniform color, and diameter greater than 6 mm. An important distinguishing feature is that benign moles do not change, while melanomas will change and grow.
Because atypical nevi are benign, they are managed conservatively with observation and maybe biopsied or excised in the event of a change. Patients with multiple atypical nevi, especially those with Familial Atypical Nevus Syndrome, should get to know their moles and conduct frequent self-examinations. In addition, they should have routine full body skin examinations from a dermatologist.