[Morphological observation of keratinizing lesion in the oral mucosa]

The purpose of this study is to examine the ultrastructure of leukoplakia and lichen planus. The light and examine electron-microscopical observations were made in the specimens of leukoplakia and lichen planus as dyskeratosis in oral mucosa which were diagnosed as benign lesions clinically and histopathologically. The results were as follows: 1. Light microscopical findings: Leukoplakia exhibited orthokeratinization and the thickening of prickle and corneal cell layers was seen. The clear and unclear granular layers were seen. Lichen planus was classified as the type of parakeratinizing region or the mixed type of orthokeratinizing and parakeratinizing region, but the former was more abundant. The thickened prickle and corneal cell layers were seen and the granular layer was unclear in the parakeratinized cell regions. Various cells were observed in expanded intercellular spaces of basal cell and prickle cell layers. The infiltration of inflammatory cells in the lamina propria was more marked in lichen planus than in leukoplakia. 2. Electron microscopical findings: 1) The melanocyte and histiocyte-like cell were seen in the expanded intercellular spaces of basal and prickle cell layers in lichen planus, while they were not observed in leukoplakia. 2) The aggregation and scattering of the discharged desmosomes into the expanded intercellular spaces of prickle cell layers were observed in leukoplakia. The number of desmosome was decreased in the orthokeratinization process from granular layer to corneal layer. An increase in the width of intercellular contact layer and the disappearance of attachment plaque were observed. In lichen planus, the desmosome of parakeratinized regions were decreased in number toward the superficial layer, but the structure was clear even in the superficial part. 3) Small number of Odland bodies in the cytoplasm of superficial layer of prickle cell layer were seen. They increased in the granular layer and were discharged into the intercellular spaces in the most superficial layer of granular layer. The lamellar pattern of Odland bodies was not clear in the more superficial layer.(ABSTRACT TRUNCATED AT 400 WORDS)