Discriminating nevus and melanoma on paraffin-embedded skin biopsies using FTIR microspectroscopy

FTIR microspectroscopy, in combination with cluster analysis, has been used to characterise skin tissues, in order to discriminate cancerous from non-cancerous ones. The main objective of this in vitro study was to demonstrate the applicability of infrared spectral imaging to separate, on paraffinised biopsies, pigmented nevi (benign skin lesions) from melanomas (malignant skin lesions). Infrared spectra were collected from paraffin-embedded samples of nevi and melanomas, without deparaffinisation. Despite the important contribution of the paraffin in these spectra, it was possible to find meaningful and discriminating spectral regions. Spectral imaging was first performed to localize different skin layers (dermis and epidermis). Spectra extracted from the images were subjected to hierarchical classification algorithm, which allowed the discrimination of melanomas from the nevi, using selected spectral windows that correspond to vibrations of DNA and melanin content. The diversity of skin lesions and direct accessibility to the skin make this organ an interesting field of investigation using this technique.