[The ultrastructure study of white sponge nevus in oral mucosa].

Biopsies from 7 patients with white sponge nevus were examined histologically. Two of them had family history. Light microscopic observation reveals that the epithelium was thickened; the spinous cell layers had enlarged and oedematous cells and ballon-like degeneration; the keratohyalin granules were increased in upper spinous cells; the superficial layers of epithelium exhibited parakeratosis and thickening. 3 specimens were examined by electron microscopy. The basal and parabasal cells were cylindrical. The cytoplasmic tonofilaments were aggregated into boundles. It was characteristics of keratinized epithelium. In middle and superficial stratum spinosum the tonofilaments were homogeneously distributed in the cell plasma and the electron-dense granulars were located near the cell boundary and attached to desmosomes by tonofilaments, unlike normal non-keratinized oral mucosa. Many Odland bodies with a lamellar structure and irregular in both size and shape were seen. It is concluded that this leasion have a dyskeratinized process. The characteristic features of keratinized oral mucosa in non-keratinized mucosa is appeared. The thickening of superficial layer is due to shedding disturbance relating to dysfunction of Odland bodies.