The accuracy of skin self-examination for atypical nevi.

We conducted a validation study to assess laypersons' ability to self-report atypical nevi. Study subjects were drawn from a large population-based cohort of middle-aged Swedish women who had responded to a previous health survey. The health survey questionnaire included color photographs of atypical nevi. Respondents were asked to examine their lower extremities for similar lesions. We invited 500 survey respondents to participate in a physician-conducted skin examination; 400 (80%) subjects agreed. We compared the results of skin self-examination for atypical nevi to the results of the physician-conducted skin examination. Using methods developed for this study, we estimated sensitivity as 29% and specificity as 85%. Positive predictive value was 20%; negative predictive value was 90%. We estimated that 12% of Swedish women have atypical nevi on the lower extremities. Although these findings suggest poor accuracy of skin self-examination for atypical nevi, our results may have been adversely affected by limiting self-examination to the legs and by the severity of atypical nevi shown in the comparison photographs used by survey respondents.