Lichen planus is a skin condition characterized by angular, purple bumps called papules that are inflammatory and pruritic (itchy). They may affect the skin, mucous membranes and nails. This noncontagious skin disease is usually mild and typically disappears without treatment in under a year, although severe cases may last much longer and may recur. Lichen planus usually affects adults between the ages of 30 and 60.

The cause of lichen planus is unknown, but it is thought to be an autoimmune disease, in which the body’s immune system attacks its own tissues. Some cases may be caused by exposure to certain chemicals (e.g., gold, iodides, antibiotics, diuretics).

Skin lesions characteristic of lichen planus may be very small or grouped together to form plaques. They are shiny, red or violet, flat-topped and covered in white spots or lines. They are usually itchy, may be scaly and their borders are distinct. They occur most often on the arms, legs, hands, feet, trunk and genitals. Mouth lesions are usually poorly defined gray-white or blue-white spots. When the nails are involved, they may be ridged, splitting, and/or thin. Hair or nail loss may also occur.

Lichen planus is typically diagnosed solely by the appearance of the lesions, although a skin biopsy from a lesion may be used to confirm the diagnosis. Treatment may not be needed. When given, treatment is generally focused on reducing symptoms (e.g., itching, inflammation) and speeding the healing time of the lesions. If the onset of lichen planus was linked to chemical exposure, it will typically clear up once this exposure has been discontinued. The most frequent treatments used are topical corticosteroids. Corticosteroids may also be injected directly into the lesions to ease itching. Severe cases may require systemic corticosteroid therapy, in either oral or injected forms.

Lichen planus is a skin disease characterized by angular, purple bumps called papules that are inflammatory and pruritic (itchy). They may affect the skin, mucous membranes and nails. Lichen planus can occur on many parts of the body, including the skin of the torso, limbs and genitals. This condition is not contagious. In most cases, lichen planus disappears without treatment in eight to 12 months, but severe cases may last three to 20 years. Generally, involvement of the mucous membranes persists longer than involvement of the skin.

The papules of lichen planus frequently appear after exposure to certain chemicals, many of them occurring in certain classes of drugs. Other chemicals also act as allergens and can produce lichen planus lesions in some people. However, most people exposed to the drugs or chemicals experience no adverse reactions.

According to the American Academy of Dermatology (AAD), lichen planus affects about 1 to 2 percent of the general population. In addition, about one in five patients who have had lichen planus have a secondary attack. It may occur at any age, but most frequently affects adults, with peak occurrence between the ages of 30 and 60. It is less common in children. All races are equally affected. Skin involvement occurs equally in men and women, but mucous membrane involvement occurs more often in women than men. The mouth is affected twice as often in women as in men.

The type of lichen planus varies by the type and location of the lesions. Many types may occur together. Types of lichen planus include:

• Erosive. Degenerative involvement of the mucous membranes, particularly the vulva, vagina and oral mucosa. Some forms may be very painful and severe.
  
  
• Guttate. Small, discrete, pinpoint lesions. These rarely become chronic (ongoing).
  
  
• Annular. Ring-like lesions with lighter centers. These almost never occur alone and are found most often in the mouth and on the male genitals.
  
  
• Hypertrophic. Large, thick, scaly patches, most often located on the front of the leg. These are usually chronic and may cause scarring.
  
  
• Atrophic. A few small, possibly scaling lesions. They often form following the resolution of annular or hypertrophic lesions.
  
  
• Bullous. Blisters that form within the papules, most often on the lower limbs or in the mouth. These tend to form from pre-existing lesions.
  
  
• Linear. Isolated lines of small lesions.
  
  
• Lichen planopilaris. Scalp involvement. Erythema (redness), irritation and hair loss are generally the first symptoms. Thick, scaly patches form on the scalp and, if untreated, may lead to scarring hair loss that is often permanent.

The cause of lichen planus has not yet been determined. However, the condition is generally considered to be an autoimmune disease, in which the antibodies of the immune system attack the body’s own tissues. Some physicians believe that several types of chemicals can trigger an immune system response in some people, causing lichen planus. Exposure to the following chemicals may be associated with lichen planus:

• Gold (used to treat rheumatoid arthritis)
  
  
• Bismuth
  
  
• Arsenic
  
  
• Iodides
  
  
• Chloroquine and quinine (antimalarial drugs)
  
  
• Antimony
  
  
• Phenothiazines (antipsychotic medications)
  
  
• Antibiotics
  
  
• Diuretics (drugs that promote the excretion of urine)
  
  
• Amalgam (a mixture of equal parts liquid mercury and alloy powder containing silver, tin, and copper used in dental fillings)

Some patients have a family medical history of lichen planus, although it does not seem to be inherited. Psychological factors (e.g., fatigue, stress) do not cause the disease, but they may make it worse.

Lichen planus is also associated with certain liver disorders, particularly hepatitis C. The association is not well understood, but individuals with these conditions are more likely to have lichen planus.

In addition, patients with mouth sores from lichen planus have a slightly increased risk of developing oral cancer. Skin involvement, however, does not increase the patient’s risk of cancer.

Lichen planus is characterized by lesions on the skin, mucous membranes or nails. Affected areas are typically mild to severely pruritic (itchy) and may be red and swollen. Skin lesions are red or violet and shiny. They are flat topped and may be about 0.8 to 1.5 inches (2 to 4 centimeters) in diameter. They may group together into rough, scaly plaques. Lesions are often covered in white spots or lacy white lines called Wickham’s striae and scales may form over them in later stages. The borders of the lesions are distinct and angular.

Skin lesions are generally symmetrical and localized. Lesions are usually distributed on both sides of the body. They occur most often on the inner surfaces of the arms, legs, hands and feet. They also appear on the trunk and genitals. However, the first signs of the condition almost always appear in the limbs. The face is rarely affected. New lesions may form from scratching or where a mild skin injury occurs. Sometimes, a dark brown discoloration may remain after the lesions disappear. This usually fades over time and is more common in people with darker skin.

Lesions on the legs are generally darker in appearance and thick patches can form on the shins. Rarely, blisters may form in the lesions. When the scalp is involved, permanent hair loss may result.

According to the American Academy of Dermatology (AAD), about 20 percent of women with lichen planus will experience some sort of genital lesions. Genital involvement is less frequent in men. Women with genital lesions may experience burning, redness and rawness in the vaginal area. Increased vaginal discharge can also occur. Sexual intercourse may be very painful and result in bleeding. Lichen planus lesions may also scar, resulting in closure of the vagina. Men most often develop lesions around the tip of the penis.

Lesions may also occur in the mouth. In some cases, the mouth is the only area of the body affected. Mouth lesions may cause dry mouth or a metallic taste in the mouth. The lesions are usually poorly defined gray-white or blue-white spots, but sometimes only Wickham’s striae (lacy patches) occur. Mouth lesions often remain unnoticed by patients, only being discovered by dentists during routine exams. However, severe forms of the condition can cause lesions that are tender and painful. Lesions are usually located on the inside of the cheeks but may also occur on the sides of the tongue or, rarely, on the gums. Sometimes, these mouth lesions erode to form painful ulcers. Some patients may find it hard to eat. Redness and bleeding of the gums may also occur.

Lichen planus lesions may also affect one or more nails on the hands or the feet. In most cases, only a few nails are affected. There may be longitudinal ridging or grooving or splitting of the nail surface and the nails may become thin. Darkening of the nail may also occur. Some cases result in nail loss that may be temporary or permanent.

A physician will begin by collecting the patient’s medical history, including a list of current medications. Because many medications are associated with lichen planus, patients must be sure to list every medication they are taking.

Lichen planus is diagnosed by evaluation of the characteristic lesions on physical examination by a physician, typically a dermatologist. If there is any question about the diagnosis, it can be confirmed with a skin biopsy from any of the lesions.

Since lichen planus is frequently associated with hepatitis C, physicians may also choose to order a blood test to check for the virus.

The symptoms of lichen planus may appear similar to several other conditions. A diagnosis of lichen planus should rule out these conditions. Conditions that may be confused with lichen planus include:

• Graft-versus-host disease. Results when the cells of transplanted tissue incite an immune attack on the patient’s tissue. Cutaneous attacks can result in eruptions similar to lichen planus lesions.
  
  
• Secondary syphilis. Secondary attack of syphilis characterized by skin rash, among other symptoms.
  
  
• Lichen simplex chronicus. Dermatitis with patchy lesions from friction on the skin.
  
  
• Pityriasis rosea. Eruptions of pink papules on the trunk, arms or legs.
  
  
• Psoriasis. A skin disease marked by red lesions covered in silvery scales. The guttate form may bear a resemblance to guttate lichen planus, whereas the plaque form may be similar to hypertrophic lichen planus.
  
  
• Ringworm (tinea corporis). Fungal skin infection that may resemble annular lichen planus.

There is no cure or specific therapy for lichen planus. However, it is usually mild and may require no treatment. Treatment generally concentrates on reducing the itching and inflammation and speeding the healing time of the lesions. Lichen planus that affects mucous membranes is typically more severe than when it affects the skin. The mucous condition may be more persistent and difficult to treat.

If the onset of lichen planus was linked to chemical exposure, it will typically clear up once this exposure has been discontinued. Further outbreaks can be prevented by avoiding the chemical cause.

Antihistamines may be used to provide comfort and relief from itching. Topical treatments for the lesions often begin with bland emollients and detergent-free soap substitutes. Corticosteroid creams and ointments are frequently prescribed to reduce inflammation and suppress immune and allergic reactions. Other topical treatments include topical retinoids and other anti-inflammatory and anti-pruritic creams to reduce itching and inflammation and to aid in healing. Dressings may be used over these topical treatments to increase absorption and protect the affected area from scratching.

Corticosteroids may be injected directly into the lesions to ease itching. Though this can be helpful, caution must be used in people with dark skin, because it may cause hypopigmentation (lighter patches of skin) around the injection site. Oral steroids may be recommended when the scalp is involved.

If mouth lesions are present, an anesthetic mouth wash may be used to temporarily numb the area and make eating more comfortable.

For severe cases, particularly with mucosal involvement, systemic corticosteroids may be used. Other medications for severe, resistant cases include topical immunosuppressants and oral antifungal and anti-inflammatory medications. In some cases, phototherapy, which uses ultraviolet light to treat the skin, may be beneficial.

Because its cause is not known, lichen planus cannot be prevented.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about lichen planus:

1. Do my symptoms indicate lichen planus?
   
   
2. What may have caused me to develop lichen planus?
   
   
3. How severe is my lichen planus likely to become?
   
   
4. Can I spread lichen planus to other parts of my body or to other people?
   
   
5. Does my lichen planus require treatment?
   
   
6. What treatment options are available to me?
   
   
7. How long is my lichen planus likely to last?
   
   
8. Is my lichen planus likely to recur?
   
   
9. Does lichen planus pose any danger to my overall health?
   
   
10. Is it likely that I may have a liver condition, such as hepatitis C, in addition to lichen planus?