Nonlinear laser imaging of skin lesions.

We investigated different kinds of human ex-vivo skin samples by combined two-photon intrinsic fluorescence (TPE), second-harmonic generation microscopy (SHG), fluorescence lifetime imaging microscopy (FLIM), and multispectral two-photon emission detection (MTPE). Morphological and spectroscopic differences were found between healthy and pathological skin samples, including tumors. In particular, we examined tissue samples from normal and pathological scar tissue (keloid), and skin tumors, including basal cell carcinoma (BCC), and malignant melanoma (MM). By using combined TPE-SHG microscopy we investigated morphological features of different skin regions. Further comparative analysis of healthy skin and neoplastic samples was performed using FLIM, and MTPE. Finally, we demonstrated the use of methyl-aminolevulinate as a contrast agent to increase the contrast in BCC border detection. The results obtained represent further support for in-vivo noninvasive imaging of diseased skin.