Oral lichen planus is usually cancerous in mucosal locations. 1. Usually whether lichen planus will be cancerous or not is mainly related to its location, most of the lichen planus that occurs in the skin will not be cancerous. If lichen planus is found in a special area, it may cause erosion, and then it may become cancerous. Part of oral lichen planus that occurs in the mucous membranes is prone to become cancerous. 2. Generally, patients with oral mucous membrane lichen planus may have recurrent reddish white spots, severe pain, or even erosion. If the erosion occurs repeatedly and even lasts for a long time, patients should be alert to the possibility of cancer. If oral lichen planus occurs, it is recommended to consult a doctor in time and under the guidance of a professional doctor to carry out the relevant examinations and treatments to avoid delaying the condition.