Dermoscopic difficult lesions: an objective evaluation of reflectance confocal microscopy impact for accurate diagnosis

BackgroundEarly detection of melanoma is the main objective to ensure a high survival rate. In some cases melanoma diagnosis still remain difficult and this leads to unnecessary excisions. ObjectiveThe aim of this study was to detect the most relevant Reflectance confocal microscopy (RCM) features for the detection of dermoscopic difficult melanomas. MethodA total of 322 lesions were selected from database and were evaluated on dermoscopy according to the 7-point checklist score, in blind from histological diagnosis. We classified the lesions into three categories: (i) featureless' lesions with score ranging between 0 and 2; (ii) positive-borderline' moles with score between 3 and 4 and (iii) positive-clear cut' lesions with score from 5 to 10. We evaluated confocal features of the featureless' lesions and of the positive-borderline' lesions. Evaluated confocal features were as follows: presence of pagetoid cells, cell shape (roundish or dendritic) and number (< 5 or >5 cells per mm(2)), overall architecture (ringed, meshwork, clods and non-specific pattern); architectural disorder, presence of cytological atypia (>5 cells per mm(2)) and cells arranged in nests. ResultsAmong 322 lesions 70 were melanomas and 252 were nevi. According to the classification based on the 7-point checklist score, 130 featureless lesions' (score 0-2) including six melanomas, and 102 positive-borderline' moles (score 3-4) including 17 melanomas, were identified. Round pagetoid cells >5 cells per mm(2) and/or architectural disorder on RCM were found in all of six melanomas with featureless dermoscopy. Round pagetoid infiltration and five or more atypical cells at the DEJ were found in 16 positive borderline melanomas'. ConclusionsRCM represents a rapid non-invasive technique that can aid early diagnosis of dermoscopic difficult melanomas. Use of RCM on lesions with clinical and/or dermoscopic suspect of malignancy may reduce the number of unnecessary excision increasing the rate of accurate diagnoses.