Résumé
The surface epithelium adjacent to 32 cases of oral squamous cell carcinoma were taken, fixed, processed and stained with routine H and E and antikeratin antibody [Dako Pat Kit K 522]. The surface epithelium adjacent to oral squamous cell carcinoma showed variable changes as normal hyperplastic, dysplastic epithelium including areas with leukoplakia and carcinoma in situ. The expression of keratin proteins in normal, hyperplastic and mild dysplastic surface epithelium showed a regular and regional distribution pattern. On the other hand, the whole thickness of the surface epithelium with moderate and severe dysplastic changes involving areas with leukoplakia and carcinoma in situ exhibited irregular immunostaining pattern where variable numbers of the basal and superbasal cells displayed positive reaction. The reaction lead to the suggestion that there was a correlation between the pattern of keratin distribution the degree of cellular differention as well as this marker can be considered as a helpful aid in the diagnosis of moderate and severe dysplasia including carcinoma in situ especially in small fragmented biopsies. Based on the staining intensity, the cell of leukoplakia can be also considered as highly differentiated cells whereas that of carcinoma in situ can be considered as less differentiated cells