In Vivo Confocal Microscopy of Melanocytic Lesions Improves Diagnostic Accuracy for Melanoma

In vivo reflectance-mode confocal laser microscopy enables the visualization of the skin at quasi- histopathologic resolution. The aim of our study was to describe confocal features in melanocytic lesions, to evaluate their diagnostic significance for melanoma identification, to develop a simple algorithm useful for diagnostic purposes. A total of 102 consecutive melanocytic lesions (37 melanomas, 49 acquired nevi and 16 Spitz nevi), corresponding to lesions with equivocal aspects at clinical and dermoscopic inspection and excised in order to rule out a melanoma, were investigated by means of confocal microscopy (Vivascope 1000). In superficial layers the general pattern and the presence and aspects of pagetoid cells were evaluated. At basal cell layer dermal papilla features and cytological aspects, suggesting the presence of cellular atypia, were described. In dermal papilla, the presence and morphology of melanocytic nests and the presence and aspect of solitary cells were evaluated. Some features were more frequently observed in melanomas. In multivariate analysis 6 features appeared independently correlated with melanoma diagnosis. The presence of non edged dermal papillae, atypical cells in basal layers and isolated nucleated cells within dermal papilla were strongly correlated with melanoma diagnosis and were considered as major criteria (scored 2 points), whereas the presence of pagetoid cells, a widespread pagetoid infiltration in superficial layers and cerebriform nests in upper dermis were considered ‘‘minor’’ criteria (scored 1 point). A total score, ranging between 0 to 9, was obtained for each lesion and a ROC curve with an area under the curve of 0.951 was obtained on our dataset. In conclusion, characterization of confocal microscopy features of melanomas and nevi seems to improve diagnostic accuracy for difficult to diagnose melanocytic lesions.