DYSPLASTIC NEVI: RISK FACTOR FOR MELANOMA

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Summary and Comment

DYSPLASTIC NEVI: RISK FACTOR FOR MELANOMA.

Dysplastic nevi have been associated with melanoma risk in some epidemiologic studies, but the data are far from convincing. This case-control study compared number and type of nevi in 716 patients who had newly diagnosed melanoma with 1,014 control subjects of the same age, sex, race, and geographic distribution.

Nevi were considered dysplastic if they were at least 5 mm in size and entirely flat. At least two of the following features were also necessary: variable pigmentation; an irregular, asymmetric outline; and indistinct borders.

Melanoma was strongly associated with number, size, and dysplastic nature of nevi. Patients with 100 or more small nevi (2 to 5 mm) had an adjusted relative risk for melanoma of 3.1 compared with patients with 0 to 24. Nondysplastic nevi greater than 5 mm were also associated with melanoma, with an adjusted relative risk of 2.3 in subjects with 10 or more nevi compared with those with none. Dysplastic nevi, however, represented the most potent risk factor, with an adjusted relative risk of 2.2 if just one was present, and of 12 if there were 10 or more.

Comment: These data demonstrate a modest increase in melanoma risk for patients with small nondysplastic nevi, and a major increase for those with dysplastic lesions.

— TH Lee

Published in Journal Watch General Medicine May 16, 1997