MELANOMA RISK IN INDIVIDUALS WITH CLINICALLY ATYPICAL NEVI

Background and Design: A lack of consensus as to the clinical and hist ologic characteristics of dysplastic nevi has resulted in the recommen dation to abandon the term dysplastic nevus for the more descriptive a typical nevus or atypical mole. The significance of the presence of on e or more such lesions, histologic features notwithstanding, has not b een carefully examined. The risk of melanoma was assessed in individua ls with atypical nevi monitored regularly in our Pigmented Lesion Clin ic. Any patient enrolled in this subspecialty clinic between 1980 and 1985 without the diagnosis of melanoma who had at least one sufficient ly atypical-appearing nevus and who was followed up for a minimum of 5 years was entered in the study. Results: A total of 155 such individu als were identified. The mean (+/- SEM) age of the patients at first e valuation was 26+/-1 years. The group was followed for 7+/-1 years. Th e male-female ratio was 1:1. A family history of melanoma was present in 71 subjects (46%). Of the 155 patients, two developed melanoma. The thickness of the tumors in both patients was less than or equal to 0. 8 mm. Twenty-five patients (16%), including the two with melanoma, had at least one nevus removed that showed severe nuclear atypia''. Concl usions: The risk of melanoma in individuals with atypical nevi is sign ificantly greater than expected. The elevated risk was demonstrated ev en though careful, regular evaluations and removal of more atypical le sions were performed. This study provides evidence that, compared with no surveillance, the meticulous monitoring of patients with clinicall y atypical nevi is more likely to result in the detection of melanoma at thin stages, with an attendant improved prognosis.