Lichen planus (LY-kin PLAN-us) is a condition of the skin and mucous membranes * that can cause shiny, reddish-purple bumps that may be itchy and painful, particularly near the genitals. The bumps may blister and cause patches of rough, scaly skin.
Lichen planus is an inflammatory * condition of the skin and mucous membranes. It is not contagious. It can appear in one or more places on the skin, most typically on the skin or inside the mouth. It can also appear on the scalp or genital area.
Lichen planus is most common in middle-aged adults. Women get lichen planus in the mouth more frequently than men do. Children and teens seldom have the skin condition, so sometimes healthcare providers diagnose it as an infection instead of lichen planus.
The cause of lichen planus is unclear. It is a disease of the autoimmune * system. In this case, the immune system interprets the cells as foreign and attacks the cells of the skin or mucous membranes (mouth). Other possible causes include viral infections * , allergic response, stress, or genetics * * and other liver diseases. Some medications, most often diuretics * and antimalarial * drugs, cause a rash that looks like lichen planus. Exposure to some chemicals may be risk factors, including antibiotics, arsenic, gold, iodide compounds, and some dyes. Metal dental fillings or braces made of nickel may cause lichen planus in the mouth. A specific type of lichen planus has been found to occur within families.
Lichen planus on the skin looks like shiny, firm, reddish-purple bumps. The lesions sometimes have thin white, scaly lines. The bumps can occur anywhere on the body, most often in areas where the limbs flex, such as the wrists and ankles. They can also appear on the lower back and, less often, on the genitals. The bumps tend to be darker on the legs. Lichen planus can cause itching and pain around the bumps and the lesions may progress to blisters that develop scabs after they burst. As more bumps appear in the same place, patches of rough, scaly skin can form. The lesions usually develop and spread over a period of two weeks to a few months.
The lesions of lichen planus in the mouth are most often found on the insides of the cheeks, under the tongue, and on the lips and gums. These bumps are usually purple with white or gray streaks. They can swell and cause pain. The person may experience dry mouth and a metallic taste in the mouth.
When lichen planus occurs on the nails, it can appear on one or more nails of either the hands or the feet. It causes ridges or grooves on the nails, which results in the nails thinning and splitting. The nails sometimes do not grow back.
Lichen planus on the scalp is rare, but when it does occur, symptoms are tiny reddish-purple bumps, scaly skin, irritation of the scalp, and hair thinning or loss.
Lichen planus is diagnosed and treated by a dermatologist, a physician who has specialized knowledge and experience in skin diseases. Usually, the dermatologist can diagnose lichen planus by examining skin lesions. A biopsy * is performed, which removes a small portion of the affected skin to examine more closely under a microscope. Other laboratory and diagnostic studies may be done to rule out other diseases.
Dentists may identify lichen planus during a person's dental examination. The dentist may then refer the person to a dermatologist for further diagnosis and treatment.
If lichen planus in the mouth causes pain, burning, blisters, or sores, medicinal mouthwashes may be prescribed. As lichen planus can contribute to gum disease (gingivitis), routine follow-up by the dentist is recommended, along with good mouth care, including brushing and flossing the teeth daily. Lichen planus in the mouth is more difficult to treat because the person is constantly eating, drinking, and talking throughout the day, which can continue to irritate the affected areas of the mouth. Because of this, the condition takes longer to go away. Sometimes, the doctor can prescribe an antibiotic that helps some people with oral lesions.
While lichen planus may not be prevented, avoiding hepatitis C infection can lower risk. People who have lichen planus can take steps to manage the condition and keep it from coming back.
See also Autoimmune Disorders: Overview • Hepatitis • Immune Deficiencies • Skin Conditions: Overview
James, William D., Timothy Berger, and Dirk Elston. Andrew's Diseases of the Skin: Clinical Dermatology, 12th ed. St. Louis, MO: Elsevier, 2015.
American Academy of Dermatology. “Lichen Planus.” AAD.org . https://www.aad.org/public/diseases/rashes/lichen-planus (accessed March 28, 2016).
Healthline.com . “Lichen Planus Overview.” http://www.healthline.com/health/lichen-planus#Overview1 (accessed March 28, 2016).
MedlinePlus. “Lichen Planus.” U.S. National Library of Medicine. http://www.nlm.nih.gov/medlineplus/ency/article/000867.htm (accessed March 28, 2016).
American Academy of Dermatology. PO Box 4014, Schaumburg, IL 60168. Toll-free: (866) 503-7546. Website: https://www.aad.org (accessed March 28, 2016).
* mucous membranes are the thin layers of tissue found inside the nose, ears, cervix and uterus, stomach, colon and rectum, on the vocal cords, and in other parts of the body.
* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that involves swelling, pain, redness, and warmth.
* autoimmune (aw-toh-ih-MYOON) is relating to a disease in which the body's immune system attacks some of the body's own normal tissues and cells.
* viral infection is an infection caused by a virus. Viral infections are treated by antiviral drugs and not antibiotics, which are used to treat bacterial infections.
* genetic (je-NEH-tik) refers to heredity and the ways in which the characteristics of an organism are transmitted from one generation to the next.
* hepatitis C (heh-puh-TIE-tis C) is an inflammation of the liver caused by an infection with the hepatitis C virus.
* diuretic (dye-yoor-EH-tik) is medication that increases the body's output of urine.
* antimalarial (an-tie-ma-LARee-ahl) drugs are used to treat malaria, a disease caused by a parasite that is transmitted by mosquitoes.
* biopsy (BI-op-see) is a test in which a small sample of skin or other body tissue is removed and examined for signs of disease.
* antihistamines (an-tie-HIS-tuh-meen) are drugs used to combat allergic reactions and relieve itching.
* corticosteroids (kor-tih-ko-STIRoyds) are drugs made in a laboratory that resemble chemical substances made by the adrenal glands that have several functions in the body. These medicines can ease inflammation and are not the same as the illegal steroids used by some athletes.
* retinoic acid (REH-tin-OH-ik acid) is a compound derived from retinol or vitamin A, often used in ointments to treat acne and other skin conditions.