Lichen planus, a recurring itchy disease, starts as a rash of small, separate, red or purple bumps that then combine and become rough, scaly patches.
The cause of lichen planus is not known, but it may be a reaction by the immune system to a variety of drugs (especially gold, beta-blockers, nonsteroidal anti-inflammatory drugs [NSAIDs], angiotensin-converting enzyme [ACE] inhibitors, sulfonylureas, antimalarial drugs, penicillamine, and thiazides). The disorder itself is not infectious. The disease may occur in people who have hepatitis C or certain liver problems.
The rash of lichen planus almost always itches, sometimes severely. The bumps are usually violet and have angular borders. When light is directed at the bumps from the side, the bumps display a distinctive sheen. New bumps may form wherever scratching or a mild skin injury occurs. Sometimes a dark discoloration remains after the rash heals.
Usually, the rash is evenly distributed on both sides of the body—most commonly on the torso, on the inner surfaces of the wrists, on the legs, and on the genital area. The face is less often affected. On the legs, the rash may become especially large, thick, and scaly. The rash sometimes results in patchy baldness on the scalp. Lichen planus is not common among children.
About half of people who get lichen planus also develop it in the mouth. Lichen planus in the mouth usually results in a bluish white patch that forms in lines. This type of mouth patch often does not hurt, and the person may not know it is there. Sometimes painful sores form in the mouth, which often interfere with eating and drinking.
Lichen planus affects the nails in up to 10% of cases. Some people may have only mild symptoms such as discoloration of the nail beds, thinning of the nails, and formation of nail ridges. Other people may completely lose their nails and have scarring from the cuticle at the base of the nail (the nail fold) to the skin under the nail (the nail bed).
Doctors typically base the diagnosis on how the rash looks and where it appears on the body. However, because many other disorders can look like lichen planus (such as lupus erythematosus on the body and candidiasis or leukoplakia in the mouth), doctors typically do a biopsy (examination of tissue under a microscope). Once diagnosed, doctors may do other tests of liver function and for hepatitis infections.
Lichen planus usually clears up by itself after 1 or 2 years, although it sometimes lasts longer, especially when the mouth is involved. Symptoms recur in about 20% of people. Prolonged treatment may be needed during outbreaks of the rash. However, between outbreaks, no treatment is needed. People with mouth sores have a slightly increased risk of oral cancer, but the rash on the skin does not turn cancerous. Lichen planus in the vagina may be chronic and hard to treat, which decreases quality of life and may cause scarring.
People who have no symptoms do not need treatment. Drugs that may be causing lichen planus should be avoided, and standard treatments can be used to relieve itching (see Itching and Noninfectious Rashes: Treatment). Corticosteroids may be injected into the bumps, applied to the skin, or taken by mouth, sometimes with other drugs, such as acitretin, griseofulvin, or cyclosporine. Phototherapy (exposure to ultraviolet light), sometimes combined with the use of psoralens (drugs that make the skin more sensitive to the effects of ultraviolet light) may also be helpful. Combining ultraviolet A light with psoralens is called PUVA (psoralen plus ultraviolet A). Use of a small band of ultraviolet B light is called narrowband ultraviolet light B (NBUVB).
For painful mouth sores, a mouthwash containing lidocaine, an anesthetic, may be used before meals to form a pain-killing coating. Lidocaine mouthwashes should not be used more frequently than prescribed. Tacrolimus ointment or corticosteroid mouthwashes, injections, or pills may also help mouth sores. Dapsone taken by mouth or cyclosporine taken by mouth or as a mouth rinse may also help.
Last full review/revision November 2012 by Peter C. Schalock, MD