What Is Lichen Planus? What Causes Lichen Planus?

Lichen planus is an inflammatory skin condition, characterized by an itchy, non-infectious rash of small, polygonal (many sided) flat-topped pink or purple lesions (bumps) on the arms and legs. Other parts of the body may also be affected, including the mouth, nails, scalp, vulva, vagina, and penis. Involvement in the scalp can result in hair loss - sometimes permanent.

Nobody knows what the exact causes of lichen planus are. We know it can be triggered by taking certain medications, including thiazide diuretics, antimalarials and phenothiazines (a group of tranquilizing drugs with antipsychotic actions). A significant number of skin specialist doctors (dermatologists) believe it might be classified as an autoimmune disease. A higher-than-normal percentage of people with hepatitis C and some other liver diseases have lichen planus.

According to the National Institutes of Health (NIH), USA, lichen planus affects between 1% and 2% of the American population. According to the National Health Service (NHS), UK, around 1 in every 50 people is affected by lichen planus.

Oral lichen planus is more common in women than in men. Skin lichen planus affects both sexes equally. It typically occurs in people over 30 years of age. About half of all affected people have oral lichen planus (symptoms in the inner surface of the mouth). Oral lichen planus typically occurs inside the cheeks, but may also affect the lips, gums and tongue.

Lichen planus symptoms on the skin can take up to two years to go away. However, once gone they hardly ever return. Oral lichen planus can take much longer to go away.

Lichen planus:

• Does not appear to be an hereditary condition - you cannot pass it on to your children
• Is not an infectious condition - you cannot catch it from somebody with the condition
• Is not a form of cancer
• Occurrence does not seem to be linked to nutrition. However, spicy foods, citrus juices, and tomato products may aggravate symptoms if there are open sores in the mouth.

The word lichen refers to the lichen plant which grows on rocks or trees, while the word planus in Latin means "flat".

According to Medilexicon's medical dictionary:

Lichen planus is an "eruption of flat-topped, shiny, violaceous papules on flexor surfaces, male genitalia, and buccal mucosa of unknown cause; may form linear groups; microscopically characterized by a bandlike subepidermal lymphocytic infiltrate. Spontaneous resolution is common after months to years."

What are the signs and symptoms of lichen planus?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign. Lichen planus of the skin:

• The rash appears abruptly, and usually lasts for several months
• There are clumps or patterns of shiny, raised, red/pink/purple, flat-topped papules (bumps)
• Papules are approximately 3mm to 5mm in diameter
• Sometimes there may be white streaks on the papules, called Wickham's striae
• Intense itching, especially at night
• Most affected areas are the wrists, elbows, ankles, and lower back. However, other parts of the body may be affected. The shins may be affected by hypertrophic (thickened) lichen planus, while the armpits may have annular (ring-shaped) lichen planus.

The first attack may continue for weeks, and even months, while recurrences can go on for years - recurrences are more common in cases of oral lichen planus. When symptoms are gone there may be dark brown or gray spots on the skin, which are more noticeable if the patient has dark skin.

Oral lichen planus (affects the mouth):

• White streaks on the inside of the cheeks. The gums, tongue and lips may also be affected.
• The streaks are not usually painful or itchy
• The white streaks are persistent (they do not go away)
• Possible redness and blistering of the gums
• Sore mouth ulcers can develop, and recur (erosive lichen planus)
• The patient's sense of taste may become blunted. Some experience a metallic taste
• Dry mouth
• Spicy foods, crispy foods, and tomato products can exacerbate symptoms

Penile lichen planus (lichen planus of the penis):

• Purple/white ring-shaped patches appear around the glans (head of the penis)
• They are not usually itchy
• Symptoms are similar to thrush, and often mistaken for thrush

Lichen planus of the vagina and vulva:

• Vulva - white streaks develop, similar to those that appear in the mouth. They are usually not itchy or painful. The skin may be red. Erosive lichen planus may affect the inner lips (labia minora) and the entrance to the vagina (introitus) - the affected mucous membrane is bright red and raw. The labia minora may shrink and stick to each other or to the labia majora (outer lips).
• Vagina - may be red. Scar tissue may distort the shape of the vagina. Lichen planus may affect deeper within the vagina, causing desquamative vaginitis. A mucky discharge appears when the surface cells in the vagina peel off. The eroded vagina may easily bleed when touched. Sexual intercourse may become difficult or impossible.

Lichen planus follicaris (lichen planopilaris) - this affects hairy areas, such as the scalp. There may be redness and irritation. Sometimes there is hair loss, which may be permanent.

Other areas - lichen planus of the anus, ear canal, eyelids and esophagus (all extremely rare).

(Erosive lichen planus is a chronic, painful condition which affects mucous membranes - mainly the mouth and the genitals.)

What are the risk factors for lichen planus?

A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.

Lichen planus can affect humans of any age or race. However, it is more common among:

• Middle-aged adults
• Females (oral lichen planus)
• Patients with liver diseases, such as hepatitis C or cirrhosis

What are the causes of lichen planus?

Experts are not sure what the exact causes of lichen planus are. Many believe it is linked to an immune system disorder, where the person's white blood cells - which defend us from bad bacteria, viruses and other germs - mistakenly attack healthy tissues of the skin, mucous membranes, and hair.

Medications - sometimes lichen planus may occur as a reaction to some medicines, such as:

• Beta-blockers - medications that relieve stress on the heart, slow the heart beat, lessen the force of heart muscle contractions, and reduce blood vessel contraction in the heart, brain, and throughout the body.
• Anti-inflammatory medications
• Gold injections - for the treatment of arthritis
• Antimalarials
• Thiazide diuretics
• Phenothiazines (a group of tranquilizing drugs with antipsychotic actions)

Some substances - there is a link between contact with some chemicals used on color photographic development and lichen planus risk.

Mercury tooth fillings - some studies have found a link between lichen planus type changes in the mouth as a result of allergy to mercury tooth fillings. Signs and symptoms go away after the fillings are replaced with non-mercury ones.

Lichen planus can be part of Grinspan's syndrome - a syndrome characterized by hypertension, diabetes and oral lichen planus.

Diagnosing lichen planus

After examining the skin and identifying the characteristic rash, a GP (general practitioner, primary care physician) may be able to diagnose lichen planus.

Punch biopsy - the doctor uses a circular tool to extract a small sample of the skin's deeper layers. Often stitches are required to close the wound. The sample is examined under a microscope to confirm a lichen planus diagnosis.

If the GP is still unsure, the patient may be referred to a doctor who specializes in skin conditions (a dermatologist).

Oral lichen planus - a dentist or oral specialist usually diagnoses oral lichen planus by taking a biopsy.

What are the treatment options for lichen planus?

Lichen planus is not a curable condition. However, when it affects the skin it usually clears within several months (sometimes this may take up to two years). Treatment focuses on easing symptoms until the rash clears. Other types of lichen planus may last much longer.

Mild cases require no treatment by the doctor, except for periodic observations.

Treatment for more severe cases may include:

• Antihistamines - usually taken at night to reduce itching.
• Phototherapy with ultraviolet light
• Topical medications (applied onto the skin):
  
  
  • Steroid creams or ointments - these can be very effective in reducing inflammation and redness. The medication is applied to the itchy spots. When the spots change color to brown or gray treatment should stop.
  • Immunosuppressants - sometimes creams or ointments may contain a steroid-sparing immune-modulating medication (drugs to reduce the immune system).
• Oral corticosteroids (steroid tablets) - for more severe cases, or when creams and ointments are not effective enough.
• Ciclosporin capsules or acetretin tablets - these lower the immune system and may sometimes help. Only used in extreme cases.
• Oral symptoms (symptoms in the mouth) - the doctor may prescribe steroid lozenges or mouth washes if mouth ulcer symptoms are uncomfortable. The tablets are dissolved in water and the patient swills the solution in his/her mouth for a few minutes, four to five times a day. Fortunately, oral lichen planus causes minimal problems and treatment is not usually required. Oral hygiene is sometimes poor among patients with pain inside their mouths, increasing the risk of gum diseases and tooth decay - it is important to maintain good oral hygiene. Talk to your doctor or dentist about this, and make sure you go to your scheduled dental visits.
• Lichen planus of the mucous membranes - treatment is difficult to get right and may take years. The doctor may prescribe oral corticosteroids as well as topical corticosteroids.

What are the possible complications of lichen planus?

After the rash has gone there may be permanent brown or grey marks on the skin - the darker the patient's skin is the more noticeable they will be.

Persistent skin lesions and mouth ulcers may slightly raise the risk of developing cancer (rare).