Abstract
BACKGROUND: Early melanomas, dysplastic melanocytic nevi, and melanocytic tumours of uncertain malignant potential (MELTUMPs) reveal similar clinic and dermoscopic findings leading to underdiagnosis of malign lesions or unnecessary excision of benign ones. High-grade dysplastic nevi and MELTUMPs in the intermediate category should be recognized and completely excised. OBJECTIVES: We evaluated the diagnostic performance of pattern analysis, ABCD rule, colour, architecture, symmetry, and homogeneity algorithm, melanoma-specific structures and asymmetry of dermoscopic features in distinguishing early melanomas, high-grade dysplastic nevi, and MELTUMPs from low-grade dysplastic nevi. METHODS: We retrospectively assessed dermoscopic images blindly to the histopathological diagnoses in a university hospital. RESULTS: One hundred forty histopathologically confirmed melanocytic lesions were included (93 low-grade dysplastic nevi, 26 thin melanomas, 17 high-grade dysplastic nevi, and 4 MELTUMPs). All dermoscopic methods had poor diagnostic performance in early melanomas and intermediate melanocytic lesions. In the multivariate analyses of dermoscopic findings, the atypical pigment network (OR: 3.58, 95% CI: 1.31-9.72), asymmetry of globules (OR: 3.17, 95% CI: 1.37-7.35), streaks (OR: 6.16, 95% CI: 1.95-19.48) and homogenous structureless areas (OR: 5.92, 95% CI: 2.36-14.92) were the significant predictive factors for melanomas and intermediate melanocytic lesions. Positive predictive values of melanoma-specific structures were shiny white structures (100%), scar-like depigmentation (85.7%), blue-white veil (72.7%), atypical blotch (72.2%), and negative pigment network (71.4%). CONCLUSIONS: Shiny white structures, atypical network, asymmetry of globules, streaks, and homogeneous structureless areas were the most significant dermoscopic findings in discriminating early melanomas and intermediate melanocytic lesions from low-grade dysplastic nevi.