The ultrastructure of geographic tongue

Two typical cases of "geographic tongue" were investigated by means of the electron microscope. Biopsy specimens of both including the white elevated and the smooth erythematous areas of the lesions were, after routine processing, studied in semithin and ultrathin sections with a JEM 7A electron microscope. Results revealed, in the white elevated areas of the lesions, subepithelial polymorphonuclear infiltrates and microabsesses, leukocyte invasion into the epithelial layer, interepithelial edema, rupture of cell juctions, rich glycogen deposits in epithelial cells, lack of differentiation into keratinized cells, and cell necrosis with exfoliation of necrotic epithelial cells and leukocytes in the surface layer. The erythematous, smooth areas revealed pathomorphologic features of healing : some mononuclear infiltrate cells in sub- and interepithelial positions, two types of basal cell, occurring in groups, with features of either typical epidermal basal cells of immature basal cells, filament and filament bundle formation in the spinous layer, the lack of a stratum granulosum, and incomplete keratinization or parakeratinization in the surface layer. Differentiation into filiform papillae was lacking in this area. The findings have been discussed in relation to the disturbances of the keratinization process.