Lichen Planus

Lichen planus is characteristically itchy and may spontaneously resolve on its own.

Lichen planus is a chronic recurrent inflammatory disorder of the skin and mucous membranes. It is characterized by small, flat-topped, polygonal bumps that may coalesce into rough, scaly plaques on the skin. There may also be involvement of the lining tissue (mucous membranes) of the mouth and/or vagina.

Lichen planus is a poorly understood skin condition. Its name is descriptive in that to some it resembles a simple plant, a lichen, which grows on rocks and tree bark, while planus is Latin for flat.

The cause of lichen planus is unknown. In certain locales, patients with extensive lichen planus seem to be more likely to have a hepatitis C virus infection of the liver. However, it seems unlikely that the virus is the cause of lichen planus in such situations.

Some drugs, such as those containing arsenic, bismuth, or gold, can produce an eruption that appears identical to 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 (Quinidine Gluconate, Quinidine Sulfate), may produce hypertrophic lichen planus of the lower legs.

Lichenoid eruptions can occur in graft-versus-host disease in people who have received bone marrow transplants. Tissue examination by a pathologist (biopsy) is frequently necessary to distinguish such lichenoid drug eruptions from classical lichen planus. Of course, stopping the offending drug is associated with the resolution of the eruption.

Lichen planus can be distinguished from eczema, psoriasis, and other common rashes purely based on its clinical appearance in that lesions are small bumps or aggregations of bumps that are flat-topped, shiny, polygonal, and purple to gray. They tend to occur at the wrists and elbows and ankles.

Individual papules contain thin white lines called Wickham's striae. When lichen planus involves mucosal tissues, such as the lips or cheeks, these white filmy, web-like lines are easy to detect. It is not unusual for lichen planus to appear at sites of trauma, especially along lines of scratches (excoriations).

Lichen planus itching varies from mild to severe.

The onset of lichen planus can be sudden or gradual. The first attack may last for weeks or months, and recurrences may happen for years. The bumps at first are 2 mm-4 mm in diameter, with angular borders and violet color. An excess of pigment (hyperpigmentation) may develop in the affected skin as the lesions persist.

• If lichen planus involves the scalp, it can permanently damage the hair follicles, producing a patch of bald skin called lichen planopilaris.
• If lichen planus involves the finger or toenails, scarring often occurs, producing permanently malformed nails.
• Ulcerative lichen planus may occur if oral or vaginal lining tissue (mucosa) is involved.

The appearance of lichen planus depends on whether the skin or the lining (mucous membranes) inside the mouth or vagina is affected:

• Skin involvement: The usual skin involvement with lichen planus consists of flat-topped lilac or violet to brown spots a few millimeters in diameter on the skin. These spots tend to be located on the inner wrists, forearms, lower legs just above the ankles, and the lower part of the back.
• A variant of this disease is called hypertrophic lichen planus. This condition appears as thick, reddish-brown lesions that are covered with scales. These spots tend to be on the shins, but they can occur anywhere on the body. This is an especially itchy and persistent (chronic) variant of lichen planus.
• Atrophic lichen planus produces slightly depressed lesions that otherwise resemble typical lichen planus.
• Mucous membranes: Lichen planus of the mucous membranes of the mouth and genitals is common. It appears as a white, lacy rash on the inside of the cheeks or the vagina and may not cause symptoms. The oral rash often occurs before any skin involvement. More troublesome, although rare, is erosive lichen planus, which can be quite sore and uncomfortable. This erosive form typically causes the patient to complain of shallow and often quite painful, recurrent ulcers in the mouth or genitals. Lichen planus of the female genitalia can involve the external vulvar mucosa and the internal vaginal mucosa. There is an association with cancer in these areas, so both the oral and vaginal tissues need to be monitored by a medical professional.
• Nail malformation may be produced by lichen planus.
• Lichen planus may involve the scalp, producing a permanent, scarring type of balding.

Most dermatologists, gynecologists, and some oral surgeons diagnose and treat lichen planus.

Usually, lichen planus is relatively straightforward to diagnose. Physicians can make the diagnosis in typical cases simply by looking at the rash. If necessary, a skin biopsy may be done to help confirm the diagnosis because, under the microscope, lichen planus is distinctive in appearance.

Because several other lichenoid eruptions resemble lichen planus a biopsy confirmation is frequently necessary. Persistent oral or vaginal lichen planus, with spots that thicken and grow together, can sometimes be difficult to distinguish clinically from whitish precancerous plaques called leukoplakia. A biopsy can be helpful in this situation.

Ulcerative lichen planus precedes the development of oral cancer in a few patients.

Most lichen planus is relatively mild. Affected individuals who do not have symptoms do not need treatment. Ultimately, there is no agreed-upon cure for this condition.

Topical corticosteroid creams or topical calcineurin inhibitors like tacrolimus or pimecrolimus may alleviate the itch and rash. For localized, itchy, thick lesions, injections of corticosteroids directly into the plaque may help. Antihistamines may blunt the itch, particularly if it is only moderate. This effect is in part due to the sedative effect of antihistamines. For oral lesions, topical steroids (cortisone) in special oral preparations are available.

In more severe lichen planus, physicians may recommend oral medications or therapy with ultraviolet light. Oral medications may include a course of oral prednisone or acitretin or griseofulvin. Occasionally, other immunosuppressive agents may be employed. However, the itching may return after the drug has been discontinued. A low-dose oral corticosteroid every other morning also may be prescribed. For painful lesions within the mouth, special mouthwashes containing a painkiller (such as lidocaine) before meals may provide some relief. Any drug or chemical suspected of being the cause of the lichen planus should be discontinued.

Although there is little objective evidence of its benefits, green tea has been suggested as a treatment for lichen planus. It is likely to be a safe approach.

Lichen planus usually goes away by itself in time. Some drugs can produce rashes that are similar in appearance to lichen planus. These rashes can be distinguished from lichen planus in that they go away when the offending drug is stopped.

Since the cause of lichen planus is unknown, there are no reliable options to prevent it.