lichen planus mouth disorder lichen planus, oral NCIT:C7406 MESH:D017676 UMLS:C0206139 A chronic, autoimmune inflammatory condition of the mucous membranes in the oral cavity that affects approximately two percent of the population and is most often seen in middle aged women. It is characterized by white, lacy patches; red, swollen tissue; papules and plaques; or open sores. The lesions are typically bilateral. SCTID:235049008 MEDGEN:60084 olp - oral lichen planus MONDO:0043923 oral lichen planus