Chromatological and immunohistochemical study of oral premalignant lesions-Evaluation of mailgnant potentiality-

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Oral leukoplakia is known as a premalignant lesion. But every leukoplakia doesn't develop malignancy and it may not necessarily be easy to distinguish the leukoplakias with verious levels of malignant potentiality. The aim of this study was to find the effective measures to evaluate the malignant potentiality of leukoplakia objectively and quantitatively.1)As to clinical finding, the color of leukoplakia is closely connected with the malignant potentiality and the leukoplakia with red component has the higher risk. Accordingly the color of the lingual leukoplakia was measured with the new-type of colorimeter without touching the object. The measured color was recorded in figures and the color difference from the normal lingual color was expressed in CIE-LAB system, the three-dimentional standard coordinates (L^*a^*b^*). In general value index (L^*) is high and chromaticness index (a^*, b^*) is low in leukoplakia. But so far as leukoplakia with severe epithelial dyspasia is concerned, the peculiar color (L^* is low and a^*, b^* is high) namely red component made its appearance.2)Concerning histopathological finding, the cytokeratin (CK) expression pattern in oral epithelium is related to the cellular differentiation level. Therefore immunohistochemical analysis of CK expression was thought to be useful aid for the objective evaluation of dysplastic change in leukoplakias. CK10 expression was seen in the epithelium with hyperorthokeratosis and CK13 in the stratum spinosum of the leukoplakia with slight dysplasia. But both CK10 and CK13 were absent in areas with increased degree of cellular atypia. CK high molecular weight, whict includes CK 1,5,10,14, was expressed strongly in the areas where the rete ridge showed irregular elongation. Expression of CK19 was normally seen only in the stratum basale, but also in suprabasal cells in the leukoplakia with severe dysplasia.