Agreement between self-assessment of melanocytic nevi by patients and dermatologic examination

Abstract

The number of melanocytic nevi is the strongest risk factor for cutaneous melanoma. As pigmented skin lesions are visible to everybody, the question has been raised about whether people can identify themselves as being at risk for melanoma through self-counting of moles. In 1991, a total of 513 central European melanoma patients and 498 controls were asked to count the total number of nevi and the number of atypical nevi on the whole body. Whole-body examination by dermatologists followed. Agreement was assessed on categorized nevus counts by means of ordinal kappa values and log-linear modeling. Study subjects significantly underestimated the total number of melanocytic nevi (p < 0.0001). Chance-corrected overall agreement was rather poor (kappa = 0.14); and the ability to detect many existing nevi was low. Agreement was higher for atypical melanocytic nevi counts (kappa = 0.37), and the sensitivity to detect more than one atypical nevus was 0.48. Self-assessment of the number of melanocytic nevi was difficult to perform accurately, and people severely underestimated the actual number. Despite these results, people should be encouraged to perform regular skin self- examination for early detection of melanoma.