Epithelial differentiation patterns in buccal mucosa affected by lichen planus.

The epithelium derived from buccal mucosa affected by lichen planus reticularis was subjected to histometric and stereologic analysis. Point counting procedures were employed to analyse a total of 2,220 electron micrographs sampled from 5 epithelial strata in 9 biopsies, 7 with distinct and 2 with faint Wickham's striae. Histologically the reticular elements presented an atrophy of the entire epithelium which had altered its differentiation pattern from that of normal buccal epithelium. The epithelium of faintly striated lichen planus differed from that of distinctly striated lichens in regard to a series of cytoplasmic organelles representing key features of stratified epithelia, i.e. the volume densities of glycogen, membrane coating granules, keratohyalin granules, cytoplasmic filaments and the cytoplasmic ground substance. The data emphasize that the clinically discernable features of reticular lichen planus of the buccal mucosa are produced by at least two different stages in the deviation of the epithelial differentiation pattern from normality, one stage (distinct striae) being more drastically altered than the other (faint straie).