Natural history of dysplastic nevi

Background : Dysplastic nevi are markers of melanoma risk and potential precursors of melanoma. Few studies have addressed the natural history of dysplastic nevi. Objective : Our purpose was to describe the changes observed in nevi over time in a cohort of our patients with dysplastic nevi. Methods : We used a historical cohort design to study 153 patients with dysplastic nevi observed for a minimum of 5 years. Physical examination at completion of the study was compared with baseline overview and close-up photographs. Lesions excised during the study interval were assessed for history of change. Results : Fifty one percent of all evaluated nevi (297 of 593) showed clinical signs of change during an average follow-up of 89 months. New nevi were common in adulthood and continued to form in more than 20% of patients older than 50 years of age. Nevi were observed to become more clinically atypical, less clinically atypical, and disappear in all age groups. In this small cohort rates of nevus change were not correlated with personal or family history of melanoma, sex, or total number of nevi. Total nevus counts and rates of nevus change were correlated with age. Conclusion : Dysplastic nevi remain clinically dynamic in adulthood. Our data suggest that the decrease in counts of dysplastic nevi associated with increasing age is only partly explained by the disappearance of nevi over time and probably reflects a tendency to larger numbers of nevi among more recent birth cohorts.