Immunohistochemical study of oral lesions of lichen planus: diagnostic and pathophysiologic aspects.

The immunophenotype of lymphoid cells in the epithelium and lamina propria of the oral mucosa were examined in patients with lichen planus, nondysplastic leukoplakia, leukoplakia with lichen planus, and other unrelated lesions. In all groups T lymphocytes were predominant; however, the T4/T8 lymphocyte ratio was higher with lichen planus than with other groups. This may be of diagnostic value in the histologic evaluation of oral lesions not typical of lichen planus. Finally, a higher percentage of Langerhans cells were observed in lichen planus. An immunologic pathogenesis of lichen planus is proposed.