Atypical moles can be larger than common moles, irregularly shaped, and of multiple colors.
Also called dysplastic moles, atypical moles may be genetic or caused by damage from sun exposure. About 1 in 10 people develop atypical moles during their lifetime. These moles are not cancerous, and need not be removed if they are not changing. Instead, atypical moles can be a sign of an increased risk for melanoma skin cancer. Therefore, people with atypical moles are recommended to have regular skin checks with a doctor.
Melanoma is a cancer of melanocytes, the cells that make pigment in the skin. This is a skin cancer that can be deadly if caught late. Some atypical (as well as common) moles can change into melanoma, but most atypical moles will never change to cancer. In fact, melanoma is more likely to develop as a new, unusual spot on normal skin, unrelated to moles. For this reason, having moles removed will not prevent melanoma. People with many atypical moles, or who have relatives who have had melanoma, may be at greater risk for melanoma.
Atypical moles are diagnosed by their appearance. Sometimes it is hard to tell the difference between atypical moles and melanoma. The doctor may use a special magnifying lens called a dermoscope to look at moles more closely. Mole mapping, taking pictures of the entire body, can also be used to monitor the skin over time. Your doctor may perform a biopsy on a suspect spot. Under the microscope, atypical moles can have unusual features that are graded as mild, moderate, or severe. If the biopsy shows a mildly or moderately atypical mole, and it has been removed fully, no further treatment is needed. Moles that are severely atypical under the microscope may need a slightly wider surgery to ensure that they do not grow back. Moles should be monitored with total body skin examinations, according to the schedule your doctor recommends.
If you have atypical moles, you should do a skin self-check on a monthly basis. Your doctor should check any moles that suddenly change in size or color or that persistently itch or bleed. In addition, if you have a spot on your skin that does not look like any of your moles (an “ugly duckling”), you should ask your doctor about it. Excessive sun exposure (or tanning bed use) increases your risk for melanoma. Protect yourself by covering up with sun-protective clothing and hats. Wear sunscreen (SPF 30 or greater) on sun-exposed skin, and minimize the time you spend outdoors when the sun is strongest, between 10:00 am and 2:00 pm.
Melanoma Research Foundationhttps://www.melanoma.org/understand-melanoma/what-is-melanoma
National Cancer Institutehttps://www.cancer.gov/types/skin/moles-fact-sheet
Skin Cancer Foundationhttp://www.skincancer.org/skin-cancer-information/atypical-moles
Conflict of Interest Disclosures: None reported.
Strazzulla LC, Kim CC. Atypical Moles. JAMA Dermatol. 2016;152(12):1408. doi:10.1001/jamadermatol.2016.3514