a nevus exceeding 5 mm in diameter, with irregular, indistinct, or notched borders and mixed tan-to-black and pink-to-red color. Microscopically these are basally nested and scattered intraepidermal melanocytes with hyperchromatic nuclei larger than those of basal keratinocytes. If multiple and associated with a family history of melanoma, these nevi have a high risk of malignant change, but isolated dysplastic nevi in the absence of a family history of melanoma are less frequently premalignant.malignant mole syndrome. SYN: dysplastic nevus syndrome.dysplastic nevus syndrome
