Skin and/or mucous membrane disease that resembles lichen, with unknown cause.Encyclopedia Entry for Lichen Planus :Lichen planus. The exact cause of lichen planus is unknown. It may be related to an allergic or immune reaction. Risks for the condition include: Exposure to certain medicines, dyes, and other chemicals (including gold, antibiotics, arsenic, iodides, chloroquine, quinacrine, quinide, phenothiazines, and diuretics) Diseases such as hepatitis C Lichen planus mostly affects middle-aged adults. It is less common in children.Mouth sores are one symptom of lichen planus. They: May be tender or painful (mild cases may not cause pain) Are located on the sides of the tongue, inside of the cheek, or on the gums Look like bluish-white spots or pimples Form lines in a lacy network Gradually increase in size Sometimes form painful ulcers Skin sores are another symptom of lichen planus. They: Usually appear on the inner wrist, legs, torso, or genitals Are itchy Have even sides (symmetrical) and sharp borders Occur alone or in clusters, often at the site of a skin injury May be covered with thin white streaks or scratch marks Are shiny or scaly looking Have a dark, violet color May develop blisters or ulcers Other symptoms of lichen planus are: Dry mouth Hair loss Metallic taste in the mouth Ridges in the nails.Your health care provider may make the diagnosis based on the appearance of your skin or mouth lesions. A skin lesion biopsy or biopsy of a mouth lesion can confirm the diagnosis.The goal of treatment is to reduce symptoms and speed healing. If your symptoms are mild, you may not need treatment. Treatments may include: Antihistamines Medicines that calm down the immune system (in severe cases) Lidocaine mouthwashes to numb the area and make eating more comfortable (for mouth sores) Topical corticosteroids or oral corticosteroids to reduce swelling and lower immune responses Corticosteroid shots into a sore Vitamin A as a cream or taken by mouth Other medicines that are applied to the skin Dressings placed over your skin with medicines to keep you from scratching Ultraviolet light therapy.Lichen planus is usually not harmful. Most often it gets better with treatment. The condition often clears up within 18 months, but may come and go for years. If lichen planus is caused by a medicine you are taking, the rash should go away once you stop the medicine.Mouth ulcers that are present for a long time may develop into oral cancer.Call your provider if: Your skin or mouth lesions change in appearance The condition continues or gets worse, even with treatment Your dentist recommends changing your medicines or treating conditions that trigger the disorder.Lichen planus - close-up Lichen planus - close-up Lichen nitidus on the abdomen Lichen nitidus on the abdomen Lichen planus on the arm Lichen planus on the arm Lichen planus on the hands Lichen planus on the hands Lichen planus on the oral mucosa Lichen planus on the oral mucosa Lichen striatus - close-up Lichen striatus - close-up Lichen striatus on the leg Lichen striatus on the leg Lichen striatus - close-up Lichen striatus - close-up.James WD, Berger TG, Elston DM. Lichen planus and related conditions.Encyclopedia Entry for Lichen Planus :Lichen Planus. Skin and/or mucous membrane disease that resembles lichen. Can be caused by Herpesviruses including HHV-3, HHV-6, HHV-7 and in rare cases to infections with Hepatitis B and C.Information from Marcello Allegretti.