Atypical mole syndrome, also called dysplastic nevus syndrome, is a disorder of the skin characterized by the presence of many mole-like tumors (nevi). Most people have 10-20 moles over their bodies. People with this syndrome often have more than 100 moles, at least some of which are unusual (atypical) in size and structure. These moles vary in size, location, and coloring. They are usually larger than normal moles (5mm or more in diameter) and have irregular borders. Changes in the appearance of these moles must be taken seriously by patients since such changes may foreshadow the onset of cancerous disease.
Individuals with atypical mole syndrome are at greater than others for developing cancer of the skin in the form of malignant melanoma. Atypical mole syndrome is thought by some clinicians to be a precursor or forerunner of malignant melanoma. This type of cancer may spread to adjacent parts of the skin or, through the blood and lymph circulation, to other organs.