Lichen planus is an inflammatory autoimmune skin disease which affects the eyes, skin, and mucosal lining of the mouth and genitalia. The disease is characterized by inflammatory and itchy blister-like eruptions on the skin or mucosa. Lichen planus is an uncommon skin complaint. It is thought to be due to an abnormal immune reaction provoked by a viral infection or a drug. Inflammatory cells seem to mistake the skin cells as foreign and attack them. Lichen planus may cause a small number of skin lesions or less often affect a wide area of the skin and mucous membranes. In 85% of cases it clears from
skin surfaces within 18 months but it may persist longer especially when affecting the mouth or genitals.
Lichen planus on the skin looks like small, raised spots with flat tops, ranging in color from pink to purple. With time, they develop white lines or spots and a purplish sheen that can be seen from a certain angle under light. The white lines are called Wickham's striae. These patches usually occur on the inner parts of the wrists, on the lower legs, on the tip of the penis or in the vagina, and on the torso. They have also been seen in the gastrointestinal tract, the bladder, the conjunctiva of the eye, and the larynx. The bumps can be extremely itchy. Areas of skin affected by lichen planus may be discolored after the condition heals. It is less common for lichen planus to appear on the scalp and nails. When it does, it leaves behind permanent changes, such as bald patches or damage to the nail. Lichen planus can also occur in the mouth, with symptoms ranging from painless white patches to sore gums and painful ulcers that make eating and drinking difficult. When lichen planus appears on mucous membranes, such as the mouth, it usually has a white, lacy appearance. Although rare, ulcerative lichen planus in the mouth can increase the risk of mouth cancer. Ulcerative lichen planus can also occur on the palms of the hands and soles of the feet. People with lichen planus are more likely to have the hepatitis C infection.
Some drugs, such as those containing arsenic, bismuth, or gold can cause a reaction that is indistinguishable from the rash of lichen planus. Exposure to certain chemicals used in the development of color photographs can also produce a similar rash. The long-term use of the drugs quinacrine or quinidine (used for malaria, certain microscopic organisms, and worms) may produce hypertrophic lichen planus of the lower legs and other skin and body- wide (systemic) disturbances. Other unusual causes of lichen planus include liver disease and what is called graft-versus-host disease in people who have received a transplant.
Lichen planus usually heals on its own within two years. Your doctor can prescribe medication such as antihistamines to relieve itching. Corticosteroids, which can be injected into the affected areas, taken by mouth, or applied to the skin, also help control inflammation and itching. People with severe lichen planus may benefit from psoralens plus ultraviolet A (PUVA) treatment, which combines drugs to make the skin more sensitive to ultraviolet light (psoralens) with phototherapy. Medicated mouthwashes can help relieve pain from ulcers in the mouth. Patients with painful ulcers on the palms or soles of the feet may find relief by applying creams containing tretinoin, then covering the affected area with a light dressing. If lichen planus symptoms occur as a reaction to certain drugs or allergies, discontinuing that drug or avoiding the products that trigger the allergic reaction can prevent lichen planus.