A dysplastic nevus, (or naevus; pl. nevi or naevi) is an atypical melanocytic nevus;

A mole whose appearance is different from that of common moles.

Dysplastic nevi are generally larger than ordinary moles and have irregular and indistinct borders. Their color frequently is not uniform and ranges from pink to dark brown; they usually are flat, but parts may be raised above the skin surface.

Dysplastic nevi can be found anywhere, but are most common on the trunk in men, and on the calves in women.

People who have them are at increased risk of developing single or multiple melanomas.

The higher the number of these moles someone has, the higher the risk; those who have 10 or more have 12 times the risk of developing melanoma compared to the general population.

Dysplastic nevi are found significantly more often in melanoma patients than in the general population.

Medical reports indicate that about 2 to 8 percent of the Caucasian population have these moles.

Heredity appears to play a part in their formation. Those who have dysplastic nevi plus a family history of melanoma (two or more close blood relatives with the disease) have an extremely high risk of developing melanoma.

Individuals who have dysplastic nevi, but no family history of melanoma, still face a 7 to 27 times higher risk of developing melanoma compared to the general population—certainly a great enough risk to warrant monthly self-examination, regular professional skin exams and daily sun protection.