Metaplastic Keratinization in the Human Buccal Mucosa

¹ Division of Oral Pathology, University of Illinois, Chicago, Illinois

The purpose of this study was a comparison of metaplastic with genetically determined keratinized mucosa. In 70 of 77 fibrous lesions of the cheek, the overlying epithelium underwent metaplastic keratinization. Changes occurred in the lamina propria, the basal boundary, and in all epithelial layers including the basal cells. In areas of transition the metaplastic changes near the normal unkeratinized mucosa were limited to the deepest layers; with increasing distance the altered layer thickened. Regions of the metaplastic mucosa with orthokeratinized epithelium were almost identical to orthokeratotic regions of the mucosa of the hard palate. Prominent epithelial ridges, large basal cells, and small average cell size appear to be characteristics of keratinized epithelium by which it differs from unkeratinized epithelium. Thickness, though regionally variable, probably has a lower maximum in keratinized than in unkeratinized epithelium. Specialization begins in, and not above, the basal layer. The observations suggested that the sequence of tissue interaction in metaplasia may be similar to that in embryonic development.