Keratin staining pattern in clinically normal and diseased oral mucosa of lichen planus patients.

The keratin pattern in oral epithelia is related to the type of terminal differentiation observed morphologically (keratinization/nonkeratinization) and to the presence or absence of epithelial dysplasia. Furthermore, it has been suggested recently that inflammatory phenomena influence the keratin expression in human gingiva. The aim of the present study was to describe the keratin pattern in oral lichen planus (OLP) lesions, which are well known to be characterized by hyperkeratinization and severe inflammatory changes, in order to elucidate the role of inflammation in keratin expression of oral epithelia. Tissue sections were stained with antikeratin antibodies directed to groups of keratins (AE1 and AE2) and to single keratin proteins (Nos. 5, 8, 13, and 19). The keratin pattern in OLP lesions differed in some respects from that of leukoplakias and frictional keratoses as characterized in previous studies. No consistent patterns for use in a diagnostic context were found. However, the changes in OLP lesions did not mimic those previously described in inflamed gingival specimens and in oral epithelial dysplasias. Thus, the results encourage further studies on the potential diagnostic use of keratin expression in premalignant oral lesions. Furthermore, the study suggests that the inflammatory reaction seen in OLP lesions does not influence keratin expression in a way comparable with the suggested influence of inflammation in gingival specimens.