Lichen Planus

Lichen planus (LP) is thought to be caused by a T cell–mediated autoimmune reaction against basal epithelial keratinocytes in people with genetic predisposition. Drugs (especially beta-blockers, nonsteroidal anti-inflammatory drugs [NSAIDs], angiotensin-converting enzyme inhibitors, sulfonylureas, gold, antimalarial drugs, penicillamine, and thiazides) can cause LP; drug-induced LP (sometimes called lichenoid drug eruption) may be indistinguishable from nondrug-induced LP or may have a pattern that is more eczematous.

Associations with hepatitis (hepatitis B infection Hepatitis B, Acute Hepatitis B is caused by a DNA virus that is often parenterally transmitted. It causes typical symptoms of viral hepatitis, including anorexia, malaise, and jaundice. Fulminant hepatitis and... read more , hepatitis B vaccine Hepatitis B (HepB) Vaccine The hepatitis B vaccine is 80 to 100% effective in preventing infection or clinical hepatitis B in people who complete the vaccine series. For more information, see Hepatitis B Advisory Committee... read more , and, particularly, hepatitis C–induced liver insufficiency) and primary biliary cholangitis Primary Biliary Cholangitis (PBC) Primary biliary cholangitis (PBC; formerly known as primary biliary cirrhosis) is an autoimmune liver disorder characterized by the progressive destruction of intrahepatic bile ducts, leading... read more (formerly known as primary biliary cirrhosis) have been reported.

Typical lesions are pruritic, violaceous (purple), polygonal, flat-topped papules and plaques. Lesions initially are 2 to 4 mm in diameter, with angular borders and a distinct sheen in cross-lighting. They are usually symmetrically distributed, most commonly on the flexor surfaces of the wrists, legs, trunk, glans penis, and oral and vaginal mucosae but can be widespread. The face is rarely involved. Onset may be abrupt or gradual. Children are affected infrequently.

During the acute phase, new papules may appear at sites of minor skin injury (Koebner phenomenon), such as a superficial scratch. Lesions may coalesce or change over time, becoming hyperpigmented, atrophic, hyperkeratotic (hypertrophic lichen planus), or vesiculobullous. Although pruritic, lesions are rarely excoriated or crusted. If the scalp is affected, patchy scarring alopecia (lichen planopilaris) may occur.

The oral mucosa is involved in about 50% of cases; oral lesions may occur without cutaneous lesions. Reticulated, lacy, bluish white, linear lesions (Wickham striae) are a hallmark of oral lichen planus, especially on the buccal mucosae. Tongue margins and gingival mucosae in edentulous areas may also be affected. An erosive form of lichen planus may occur in which the patient develops shallow, often painful, recurrent oral ulcers, which, if long-standing, rarely become cancerous. Chronic exacerbations and remissions are common.

Vulvar and vaginal mucosae are often involved. Up to 50% of women with oral mucosal findings have undiagnosed vulvar lichen planus. In men, genital involvement is common, especially of the glans penis.

Nails are involved in up to 10% of cases. Findings vary in intensity with nail bed discoloration, longitudinal ridging and lateral thinning, and complete loss of the nail matrix and nail, with scarring of the proximal nail fold onto the nail bed (pterygium formation).

Although the diagnosis of lichen planus is suggested by appearance of the lesions, similar lesions may result from any of the papulosquamous disorders, lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more , and secondary syphilis Secondary syphilis Syphilis is caused by the spirochete Treponema pallidum and is characterized by 3 sequential symptomatic stages separated by periods of asymptomatic latent infection. Common manifestations... read more , among others. Oral or vaginal lichen planus may resemble leukoplakia Premalignant (dysplastic) changes Growths can originate in any type of tissue in and around the mouth, including connective tissues, bone, muscle, and nerve. Most commonly, growths form on the lips, the sides of the tongue,... read more , and the oral lesions must also be distinguished from candidiasis Candidiasis (Mucocutaneous) Candidiasis is skin and mucous membrane infection with Candida species, most commonly Candida albicans. Infections can occur anywhere and are most common in skinfolds, digital... read more , carcinoma Overview of Skin Cancer Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. The incidence is highest among outdoor workers, sportsmen, and sunbathers and is inversely related... read more , aphthous ulcers Recurrent Aphthous Stomatitis Recurrent aphthous stomatitis (RAS) is a common condition in which round or ovoid painful ulcers recur on the oral mucosa. Etiology is unclear. Diagnosis is clinical. Treatment is symptomatic... read more , pemphigus, mucous membrane (cicatricial) pemphigoid Mucous Membrane Pemphigoid Mucous membrane pemphigoid is the designation given to a heterogeneous group of rare chronic autoimmune disorders that tend to cause waxing and waning bullous lesions of the mucous membranes... read more , and chronic erythema multiforme Erythema Multiforme Erythema multiforme is an inflammatory reaction, characterized by target or iris skin lesions. Oral mucosa may be involved. Diagnosis is clinical. Lesions spontaneously resolve but frequently... read more .

Typically, biopsy is done.

If lichen planus is diagnosed, laboratory testing for liver dysfunction, including hepatitis B and C infections, should be considered.

Many cases resolve without intervention, presumably because the inciting agent is no longer present. Recurrence after years may be due to reexposure to the trigger or some change in the triggering mechanism. Sometimes treatment of a previously occult infection, such as a dental abscess, results in resolution.

Vulvovaginal lichen planus may be chronic and refractory to therapy, causing decreased quality of life and vaginal or vulvar scarring. Oral mucosal lesions usually persist for life.

Asymptomatic lichen planus does not require treatment. Drugs suspected of triggering lichen planus should be stopped; it can takes weeks to months after the offending drug has been stopped for the lesions to resolve.