Dysplastic naevus vs. in situ melanoma: digital dermoscopy analysis

BACKGROUND: To date, much confusion exists about the biological significance of dysplastic naevi and about the relationship between melanocytic dysplasia and clinical atypia. OBJECTIVES: To use a digital dermoscopy analyser with a series of 'borderline' pigmented skin lesions (i.e. dysplastic naevi and in situ melanomas) to find correlation between the studied variables and to determine their discriminating power with respect to histological diagnosis. METHODS: The pigmented skin lesions (n = 174) were histologically examined by three experienced dermatopathologists and identified as in situ melanomas (n = 38) and dysplastic naevi (n = 136). The system evaluated 48 parameters as possible discriminant variables, grouped into four categories: geometry, colours, textures and islands of colour. Once the lesions were analysed (stepwise discriminant analysis), sensitivity, specificity and accuracy were calculated. RESULTS: At the end of the stepwise procedure the percentage of cases classified correctly was 71.8%. Of 136 dysplastic naevi only 98 were classified correctly, while 27 of 38 in situ melanomas were recognized correctly. CONCLUSIONS: We conclude that there are so far no digital dermoscopic criteria that can clearly distinguish dysplastic naevi from in situ melanomas.