Multispectral autoflourescence detection of skin neoplasia using steady-state techniques

In the current study were used excitation-emission matrices (EEMs) and synchronous fluorescence spectroscopy (SFS) steady-state techniques in a broad spectral regions (excitation at 220-500 nm and emission at 280-850 nm) to achieve the whole set of endogenous fluorophores, existed in normal and neoplastic cutaneous tissues. Several types of benign, dysplastic and malignant types of skin lesions were investigated ex vivo using both EEM and SFS modalities, namely the basal cell papilloma and carcinoma, pigmented nevi, dysplastic nevi, squamous cell carcinoma and malignant melanoma. Histological analysis was used as a "gold standard" for evaluation of clinical diagnosis of the lesions investigated. Comparison with the normal skin tissue spectral data was made, based on the signals detected from the safety margins areas of the surgically excised tumours. EEM and SFS data reveal statistically significant differences between variety of benign, dysplastic and malignant lesions, which could be used as fingerprints, applicable for differentiation algorithms. In a few of malignancies endogenous porphyrins signals were even observed, but in general the fluorescence signals were addressed to the coenzymes, such as NADH, flavins; structural proteins, such as collagen, elastin and their cross-links, as well as keratin in the case of basal cell lesions. Pigments, such as hemoglobin and melanin distorted the signal due to intrinsic fluorophores signal reabsorption, what has to be taken into account when the algorithms for discrimination of the pathology types are developed.