IN-SITU INFRARED HISTOPATHOLOGY OF KERATINIZATION IN HUMAN ORAL OROPHARYNGEAL SQUAMOUS-CELL CARCINOMA/

Fourier transform infrared (FTIR) microspectroscopy is emerging as a p romising new tool for histopathological investigations of tissue histo chemistry. This study was designed to assess whether changes in tissue biochemistry induced by well-differentiated and poorly differentiated oral/oropharyngeal squamous cell carcinoma (SCC) can be detected by i nfrared spectroscopy. The biopsies analyzed were each proven SCC posit ive and compared with tissue taken from the contralateral normal site. Individual infrared spectra, recorded from specific tissue areas, wer e correlated with histopathological structures normally found in the o ral mucosa. Infrared mapping of these areas allows the generation of b iochemical images of molecular structures such as lipids, sugars, and proteins. The visualization of DNA and tissue structures containing ke ratin (well expressed in all epithelia) reveals distinct differences b etween normal and SCC-positive biopsies. Bivariate histogram analysis of cell components (e.g., DNA and keratin) indicated that cancer cells produce a relatively homogeneous and clearly abnormal cell biochemist ry, whereas differentiated epithelial cells present a very heterogeneo us distribution of cellular components. Using these features, tissue c ontaining abnormal or cancer cells can easily be distinguished from no rmal epithelial structures. The abnormal keratin distribution in poorl y differentiated SCC and in keratin pearls (present only in well-diffe rentiated SCC) offers insight into the process of malignant tissue tra nsformation in squamous epithelium. Applying infrared microspectroscop y in combination with bivariate statistics to histopathological tissue thin sections provides a potential diagnostic tool for detection of c ell changes in epithelial cancers.