High resolution diagnosis of common nevi by multiphoton laser tomography and fluorescence lifetime imaging.

Background Multiphoton Laser Tomography ( MPT) has developed as a non-invasive tool that allows real-time observation of the skin with subcellular resolution. MPT is readily combined with time resolved detectors to achieve fluorescence lifetime imaging ( FLIM). The aim of our study was to identify morphologic MPT/FLIM descriptors of melanocytic nevi, referring to cellular and architectural features. Methods In the preliminary study, MPT/FLIM images referring to 16 ex vivo nevi were simultaneously evaluated by 3 observers for the identification of morphologic descriptors characteristic of melanocytic nevi. Proposed descriptors were discussed and the parameters referring to epidermal keratinocytes, epidermal melanocytes, dermo-epidermal junction, papillary dermis and overall architecture were selected. In the main study, the presence/absence of the specified criteria were blindly evaluated on a test set, comprising 102 ex vivo samples (51 melanocytic nevi, 51 miscellaneous skin lesions) by 2 observers. Results Twelve descriptors were identified: 'short-lifetime cells in the stratum corneum', 'melanin-containing keratinocytes', 'dendritic cells', 'small short-lifetime cells' in the upper and lower layers', 'edged papillae', 'non-edged papillae', 'junctional nests of short-lifetime cells', 'dermal cell clusters', 'short-lifetime cells in the papilla', 'monomorphic and regular histoarchitecture', 'architectural disarray'. Conclusion Identified descriptors for benign melanocytic lesions proved sensitive and specific, enabling the differentiation between melanocytic nevi and non-melanocytic lesions. [ABSTRACT FROM AUTHOR]