Dysplastic nevi syndrome, also known as familial melanoma syndrome is the overdevelopment of abnormal/atypical moles.  Dysplastic Nevi Syndrome is an inherited condition characterized by multiple atypical moles and an increased risk of melanoma.  This disorder is also called FAMMM (Familial Atypical Multiple Mole and Melanoma syndrome).

Those with DNS tend to acquire melanoma at an earlier age than those without abnormal moles. For individuals with DNS, having a family member who has had melanoma increases the risk of developing melanoma. About two to eight percent of the Caucasian population has these moles and those with two or more close blood relatives that have the disease, have an increased risk of developing melanoma, a serious type of skin cancer.  However, those individuals who have dysplastic nevi syndrome and have no family history of melanoma, have a 27 times higher risk of developing melanoma compared to the general population. Individuals with this disorder have many large moles with differing shades of color. This predominantly develops in patients with a clear complexion, blue eyes, and the presence of numerous nevi. Lesions are located mainly on the upper trunk, back, limbs, abdomen and arms. The number of moles can range from 50 to over 100.  At least one of the moles is over 8 mm in diameter. At least one mole will have abnormal features such as: asymmetry, variable color within the mole, irregular borders, size over 6mm, or rapid change in appearance.  If you suspect you may have atypical moles or atypical mole syndrome, make an appointment with your dermatologist at your earliest conveniences. The doctor may examine the mole(s) with a dermatoscope, or may perform a biopsy.