Lichen planus and lichenoid reactions of the oral mucosa.

Oral lichenoid reactions represent a common end point in response to extrinsic agents (drugs, allergens), altered self-antigens, or superantigens. Oral lichen planus, a common and under-recognized inflammatory disorder, shares many clinical and histopathological features with oral lichenoid drug reaction and oral lichenoid contact reaction. Clinical presentation can vary from asymptomatic white reticular striae to painful erythema and erosions. Cutaneous and additional mucosal involvement is common. Delay in diagnosis of extraoral mucocutaneous lichen planus (LP) results in conjunctival scarring; vaginal stenosis; vulvar destruction; and stricture of the esophagus, urethra, and external auditory meatus. Although the etiology of LP is idiopathic, oral lichenoid reactions may be caused by medications or exogenous agents such as cinnamates and other flavorings. The clinical features, evaluation, and management of these oral lichenoid reactions are discussed.