Lichen planus and lichenoid lesions of the oral cavity.

Lichen planus is a mucocutaneous disease of unknown cause that has its principal clinical manifestations in the skin and mucosa of the oral cavity. The natural history of the cutaneous form is one of spontaneous resolution over time, while oral lichen planus pursues a much more chronic course with a low order of resolution. Oral lichen planus must be distinguished from lichenoid lesions, including lichenoid dysplasia. Malignant change in oral lichen planus is rare and is prompted by carcinogenic cofactors. There is no increased risk of development of carcinoma in cutaneous lichen planus.