Ultrastructure of oral leukoplakia and lichen planus. I. Basal region and inflammatory cells.

Nine cases of homogenous leukoplakia and 21 cases of lichen planus (11 reticular and 10 erosive) were studied under the electron microscope. The changes found in leukoplakia were limited to occasional breaks in the basal lamina and modest changes in the cytoplasm of the basal cells. The basal lamina in lichen planus was found to exhibit 3 distinctly different pictures reflecting the clinical types of lichen planus. The structural abnormalities in the basal cells increased with increasing severity of the lesions. The inflammatory infiltrate in lichen planus was found to contain mainly small-to-medium-sized lymphocytes but plasma-cells with widely dilated rough endoplasmic reticulum containing a granular substance were frequently seen. Similar changes are seen in other disorders and, therefore, specific diagnostic criteria cannot be established on the basis of the present material.