An oral condition characterized by bilateral, reticular, white, interlacing lines or striations present on the buccal mucosa, tongue, and occasionally on the lips. The gingivae may appear fiery red and the mucosa may be erythematous and show areas of erosion or ulceration (desquamative gingivitis). Skin lesions may also be present on the wrists or shins. The condition is usually asymptomatic and is more common in middle-aged women than men. The cause is unknown but lesions are the result of a cell-mediated immune reaction. If the condition is painful, treatment with topical corticosteroids may give symptomatic relief. Lesions that clinically resemble lichen planus (lichenoid) may be caused by drugs (e.g. antihypertensive drugs for high blood pressure and oral hypoglycaemic drugs for diabetes) or reactions to dental materials such as amalgam.