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Telephone: 404-851-1766 Toll Free: 866-851-5030

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Patient Education

Atypical / Dysplastic Nevi (Atypical Moles)

Atypical melanocytic nevi, or atypical moles, are proliferations of pigment cells (melanocytes) in the skin that display an unusual appearance when examined clinically or microscopically. These moles are usually harmless but may clinically resemble a malignant tumor of melanocytes known as a malignant melanoma.  Many terms have been used for atypical moles including Clark’s nevi, B-K moles, and dysplastic nevi. Atypical nevi usually have the following clinical characteristics.  They are usually larger than most moles (>5 mm), display an irregular border or an unusual asymmetric shape, and have variations in their color and texture. Some atypical nevi may resemble a “fried egg” or “wreath” with a central dark area and lighter areas peripherally. Atypical nevi most commonly occur on the chest, back, abdomen, arms, and legs. The scalp, breasts, and groin are also common locations. Most of these atypical nevi occur in fair skinned individuals and develop in the first two decades of life.

 

Many clinically atypical nevi are referred to as dysplastic nevi.  However, the term dysplastic nevus is most appropriate for a type of melanocytic nevus that has a characteristic appearance under the microscope. Only a fraction of clinically atypical nevi may show this microscopic appearance. Sometimes a grading system for the degree of dysplasia (atypia) under the microscope is used. Dysplasia may be graded on a spectrum as mild, moderate or severe. Lesions that have more severe grades tend to share more microscopic features in common with a malignant melanoma.  In some cases, a melanoma may also arise in association with a dysplastic nevus.

 

Atypical nevi may occur sporadically in individuals or can be inherited (familial). Persons with sporadically occurring atypical nevi generally only have a few such lesions (1-10). When atypical nevi run in families, it is known as the Familial Atypical Mole and Melanoma Syndrome (FAMM Syndrome / dysplastic nevus syndrome).  Affected individuals usually have numerous atypical nevi (>50) that show dysplastic features under the microscope.  There is usually a family history of melanoma in a close relative.  In general, people that have atypical nevi tend to have an increased risk of developing a malignant melanoma. The risk is increased in those with more numerous lesions. Patients with the FAMM syndrome generally have an extremely high risk of developing melanoma.

 

Patients with atypical nevi should see a skin specialist (dermatologist) regularly for skin exams. They should also be instructed on performing a self skin exam to look for any moles that may be changing or new. For patients with numerous atypical nevi, total body photography at regular intervals is a reasonable approach to monitor lesions. Some atypical nevi can be very difficult to clinically distinguish from a malignant melanoma with the naked eye. Dermatologists may use certain tools such as a dermatoscope to more closely examine such lesions. In many cases, the lesions are often removed for microscopic examination (biopsy). The lesion can then be evaluated for atypical microscopic features and the need for any further treatment.

 

logo-2 Finan Templeton Dermatopathology Associates 1200 Lake Hearn Drive, Suite 300     Atlanta, GA 30319     T: 404-851-1766