What is lichen planus?
In dermatology, the word ‘lichen’ means small bumps on the skin and ‘planus’ means ‘flat’, so the name comes from a description of the rash’s appearance. Lichen planus is a fairly common (0.2-1% of the population worldwide), itchy, non-contagious rash that usually occurs in adults between the ages of 40 to 60. It is rare in children. It affects all ethnicities equally; however oral disease affecting the lips and inside the mouth, may be more common in patients from the Indian subcontinent originally.
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What causes lichen planus?
The cause of lichen planus is still not clear, but it is thought to be related to an over-reaction in the skin’s defence/immune system. Infection with certain viruses such as Hepatitis, Human Herpes virus and Varicella Zoster virus (chickenpox virus) have also been implicated as triggers. Rashes that look like lichen planus – known as ‘lichenoid drug eruptions’ – are sometimes provoked by taking medicines for raised blood pressure or anti-malarial tablets. Stress and anxiety may also serve as triggers for its development.
Is lichen planus hereditary?
No, it is not hereditary; however, the tendency to get lichen planus can sometimes run in families especially twins.
What are the symptoms of lichen planus?
Lichen planus on the skin is usually, but not always, itchy.
What does lichen planus look like?
The rash is made up of clusters of shiny, slightly raised pink or purple-red spots (papules), usually measuring 1-3 mm in diameter. A close look may show fine white streaks on their surface. The rash usually affects the insides of the wrists, around the ankles and on the lower back, but can spread more widely. Lichen planus can also appear in a line where the skin has been scratched or injured (this is called Koebner’s response). The rash can heal to leave marks which are darker than the original skin colour.
Other types of lichen planus include:
- Thickened (‘hypertrophic’) lichen planus, which tends to affect the shins and can look like warts.
- Ring-shaped (‘annular’) lichen planus, which tends to affect the armpits.
- Lichen planus of the scalp can cause patches of hair loss in areas affected which do not usually re-grow.
- Annular lesions can also sometimes develop in sun exposed sites known as (‘actinic’) lichen planus.
- Finger and toenails can be affected, with thinning of the nail plate, or the nails becoming rough and grooved.
- Lichen planus often affects the inside of the cheeks and the gums, and this can be seen in about 50% of people who have it on the skin (see Patient Information Leaflet on Oral Lichen Planus).
- Lichen planus can affect the penis causing purple or white ring-shaped (annular) patches. Unlike lichen planus on other body parts, they often do not itch.
- Lichen planus can affect the genital area in women too and can sometimes be difficult to treat.
- In some patients oval grey-brown flat marks appear on the face and neck or trunk and limbs without a preceding rash. This is called Lichen planus pigmentosus.
- Lichen planus can sometimes blister (bullous lichen planus), however this is rare and usually affects the lower legs.
How will lichen planus be diagnosed?
The diagnosis of lichen planus is usually clinical and can be made by a Doctor examining the rash. It may sometimes be difficult to decide between lichen planus and eczema, warts or a rash caused by medication. If there is uncertainty, the diagnosis can be confirmed by a Dermatologist who may decide to arrange a skin biopsy. The skin is then looked at under the microscope.
Can lichen planus be cured?
No, treatment controls the condition but does not cure it. However, in most patients lichen planus will heal within 18 months, and not return, although some patients may have further episodes many years later. Unfortunately, some types of lichen planus, such as those affecting the scalp, nails, mouth or genitalia, can last for many years. Even after active lichen planus has cleared, darker stains than the original skin colour may persist on the skin for a long time, particularly in Asian or Afro-Caribbean skin.
How can lichen planus be treated?
Mild lichen planus without irritation does not need any treatment.
Moderate lichen planus of the skin
Affected areas are usually treated with steroid creams or ointments. Strong (potent) steroids are usually needed to calm the itchiness of the rash. These should be applied carefully once or twice a day, as instructed by your doctor. As the rash and itch clear, the red-purple spots change to grey- or light-brown flat marks. At this stage, the skin no longer requires treatment with a steroid (doing so will raise the risk of side effects such as thinning of the skin). These marks will slowly fade with time. The non-steroid prescription-only medication tacrolimus ointment and pimecrolimus cream may also be helpful for lichen planus, especially on the face, armpits and groins as they do not carry any risk of causing skin thinning.
Severe or widespread lichen planus
For severe or widespread lichen planus, the mainstay of treatment is with a course of steroid tablets. If there is little improvement in the rash, second line treatment with narrow band UVB therapy or acitretin (a tablet treatment) may be considered. If there is a poor response to second line treatment, third line tablet treatments including methotrexate, and hydroxychloroquine can be considered. These drugs were not developed to treat lichen planus (it is not in their product license), but there is some evidence that they may be helpful. These treatments do not cure the rash and it is likely to worsen if they are stopped prematurely. Treatment must be carefully monitored with blood tests and like any medicine, the risks of harmful effects versus benefits need careful consideration by the Dermatologist and patient.
Lichen planus in the mouth
Lichen planus of the hair or nails.
If lichen planus is affecting your hair or nails, the damage can be permanent. This is sometimes an indication for treatment with tablets such as Methotrexate.
Self care (What can I do?)
Try to avoid injuring or scratching your skin as it can make new spots of lichen planus appear, particularly in an active phase.
Image American Academy of Dermatology.