In vivo dermoscopic and confocal microscopy multistep algorithm to detect in situ melanomas

S. Borsari, R. Pampena, E. Benati, C. Bombonato, A. Kyrgidis, E. Moscarella, A. Lallas, G. Argenziano, G. Pellacani, C. Longo

Although several dermoscopic features of in situ melanoma (MIS) have been identified, data on confocal features for MIS are still lacking. To identify RCM (reflectance confocal microscopy) features of MIS and to develop a diagnostic score for MIS while combining dermoscopy and RCM. 120 MIS and 213 nevi (test set) were retrospectively analysed to assess the presence of dermoscopic and RCM criteria. Facial and acral lesions have been excluded. Spearman's correlation, univariate and multivariate regression models were performed to find features significantly correlated with MIS diagnosis. Multivariate results on the test set allowed the development of a multi-step algorithm, that was tested on a validation set counting 100 lesions. Dermoscopic atypical network and regression resulted as independent predicting factors for MIS diagnosis (OR=3.437, 95%CI=1.696-6.966 and OR=4.168, 95%CI=1.930-9.002 respectively). Significant confocal predictors for malignancy were epidermal pagetoid spread (OR=2.829, 95%CI=1.324-6.043) and junctional cytological atypia (OR=3.390, 95%CI=1.383-8.305 if focal, OR=8.439, 95%CI=3.213-22.165 if widespread). A multi-step diagnostic algorithm able to predict MIS with a sensitivity of 92.5% and a specificity of 61% was developed. The validation set confirmed the high diagnostic value (sensitivity 92%, specificity 58%). An easy and reproducible multi-step algorithm for MIS detection is suggested, that can be routinely used in tertiary centres. This article is protected by copyright. All rights reserved.