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Lichen Planus

 

What are the aims of this leaflet?

This leaflet has been written to help you understand more about lichen planus. It tells you what it is, what causes it, what can be done about it, and where you can find out more about it.

What is lichen planus?

Lichen planus is a fairly common, itchy, non-infectious type of rash that usually occurs in adults. The origin of the term ‘lichen planus’ is obscure. Lichen is a type of plant that lives on rocks, and its surface is made up of small groups of bumps that may look a bit like those seen in lichen planus. ‘Planus’ means ‘flat’, and tells us that the small itchy bumps that make up the rash of lichen planus have shiny flat tops.

What causes lichen planus?

The cause of lichen planus is still not known, but is likely to have something to do with the body’s immune system. Some patients, who have lichen planus only in their mouths, where their cheeks touch amalgam fillings, are allergic to mercury – as can be shown by a skin test called patch testing. However this allergy accounts for only about 20% of cases of lichen planus in the mouth, and is not relevant to lichen planus of the skin alone, or even to lichen planus of both the skin and mouth. Rashes that look like lichen planus – known as ‘lichenoid drug eruptions’ – are sometimes a reaction to taking medicines such as gold (used for arthritis) or antimalarial tablets. Lichen planus is not contagious

Is lichen planus hereditary?

Usually it is not; but, rarely, a few members of the same family can have it.

What are the symptoms of lichen planus?

Lichen planus on the skin is usually itchy. In the mouth, if symptoms occur at all, they are like those of a mouth ulcer (burning, stinging and pain) and may get worse after eating spicy foods, citrus fruits etc.

What does lichen planus look like?

The rash is made up of shiny, 3-5mm, slightly raised purple-red spots. A close look is needed to see the irregular white streaks that lie on the surface of some of them. The spots arise most often on the fronts of the wrists, around the ankles and on the lower back, but can spread more widely. In addition, lichen planus sometimes comes up in lines where the skin has been scratched or cut.

Other types of lichen planus include a thickened (‘hypertrophic’) lichen planus, which tends to affect the shins, and a ring-shaped (‘annular’) lichen planus, which usually comes up in the creases such as the armpits. Lichen planus occasionally appears on the scalp, where it can cause hair loss, or may damage the nails, (thinning and grooving of the nail plate), though this is rare.

Lichen planus is common in the mouth, usually showing up as a white lacy pattern of streaks inside the cheeks. It is present in 50 to 75% of those who have lichen planus on their skin. Usually it gives no symptoms and needs no treatment. In some patients, however, the mouth is the only area to be affected. Persistent mouth ulcers due to lichen planus can, very rarely, give rise to cancerous changes within the ulcer, and so need to be monitored by a doctor or dentist.

Lichen planus can affect the penis in men, causing purple-coloured or white ring-shaped patches looking rather like thrush. Unlike other patches of lichen planus, these often do not itch. Lichen planus can affect the genital area in women too, but this is less common.

Most patients with lichen planus clear up within 18 months and usually stay clear, although some have a second episode many years later. Unfortunately some types of lichen planus, such as oral ulceration, or hair and nail involvement, can last for many years. Even after the active lichen planus has cleared up, pigmented stains in the skin may persist for a long time, particularly in Asian or Afro-Caribbean skin.

How will lichen planus be diagnosed?

Usually the diagnosis of lichen planus can be made easily enough just by the look of the rash. Confusion may arise with flat ‘plane’ warts, with some types of eczema, and with rashes due to some drugs. If there is real doubt, the diagnosis can be clinched by looking under the microscope at a small sample of skin (a biopsy specimen) removed after a local anaesthetic injection.

Can lichen planus be cured?

No, treatment damps it down but does not switch it off. However lichen planus usually goes away by itself (see above).

How can lichen planus be treated?

  • Mild cases of lichen planus need no treatment.
  • Lichen planus on the skin.
    Skin lesions are usually treated with steroid creams. Because lichen planus can be very itchy, the steroid creams used are often strong: and it is important to use them in the right way. As lichen planus gets better, it changes from red to purple, and then to a greyish or brown colour. Treating the brown spots with steroids will not make them go away any faster, but will raise the risk of side effects such as thinning of the skin. The strong creams should be used for the red or purple itchy spots, and then stopped as they go brown.
  • Lichen planus in the mouth.
    Steroid lozenges, special sticky forms of steroid ointments, and mouthwashes can help lichen planus in the mouth, but should be used only if it is causing symptoms. One effective but slightly complicated mouthwash contains Betnesol or Predsol tablets, dissolved in 20ml of warm water and swilled around the mouth for 5 minutes four or five times daily.
  • Severe lichen planus.
    If your lichen planus is very bad, your doctor may suggest treatment with steroid tablets, ciclosporin capsules, or a tablet known as acitretin. These treatments will suppress but do not cure lichen planus, and can have important side effects and interactions with other medicines. They will not be prescribed unless your rash is very severe.
  • Lichen planus of the hair and nails.
    If lichen planus is affecting your hair or nails, the damage can be permanent – and so this is sometimes an indication for treatment with the tablets mentioned above.
  • PUVA therapy.
    A special form of ultra-violet light treatment (PUVA) may help widespread lichen planus; but it has some important long-term side effects, which your dermatologist will discuss with you.

What can I do?

  • Avoid rough or spicy foods if you are getting problems in your mouth.
  • You should be careful not to injure your skin as this can make new spots of lichen planus come up there.

Where can I get more information about lichen planus?
Web links to detailed leaflets:
www.aad.org/pamphlets/lichen.html
www.dermnetnz.org/dna.lichen.planus/info.html
www.emedicine.com/derm/topic233.html