Lichen planus (pronounced LY-KEN PLAN-US) is a fairly common skin disease which affects 1-2% of the population. It is somewhat unique among rashes because it can affect skin, mucous membranes, hair, and nails. In this article, we will focus mainly on lichen planus of the skin and mouth.
Skin Lichen Planus
Lichen planus of the skin affects all races and men and women equally between the ages of 30 and 60 years. It was first recognized in 1869. The rash consists of many small reddish purple bumps that are extremely itchy. While the rash can occur anywhere on the body skin, the most common areas are the inside of the wrists and ankles, hands and feet, waistband area, neck, and mid-low back. Facial involvement is rare. The diagnosis can be established with certainty with a skin biopsy.
When the bumps begin to flatten either with treatment or spontaneously, they leave a dark brown stain (not a scar) that will eventually fade. If the skin of a person with lichen planus is scratched deeply or cut, even if by planned surgery, the healing injury may turn into lichen planus. This unusual phenomenon can also be seen with psoriasis.
Cause and Treatment
While the cause is unknown, the conventional wisdom is that the skin disease is an inflammatory reaction in the skin caused by a malfunction of the immune system or a hypersensitivity reaction to an infection, such as a urinary tract infection, or an allergic reaction to a drug. Many drugs have been associated with lichen planus, but the more common ones in my experience are the non-steroidal anti-arthritis drugs such as naproxen and the common water pill called hydrochlorothiazide (HCTZ).
Naturally, if there is an infection, that should be treated with the appropriate antibiotic. Sometimes the rash will fade rapidly if the infection was the cause of the lichen planus. Stopping the suspected drug may also bring about successful clearing of the skin, although that may take several weeks to occur. The majority of cases, however, will not respond to antibiotics or drug removal, because their disease is a sign of autoimmunity. In other words, the patient’s own immune system, in the form of circulating lymph cells, is attacking the top layer of skin (the epidermis) which produces the visible rash.
The majority of lichen planus patients are treated with potent prescription corticosteroid ointments which help to flatten bumps and reduce itching. We may also recommend anti-histamines which also improve itching and sleeping at night. For more widespread lichen planus rash, we may give a long-acting injection of the steroid in the office, or prescribe prednisone pills for a few weeks. Sometimes these measures put the lichen planus into a quiet state for a while, but there is a strong tendency for it to recur. Steroid-resistant cases of lichen planus may respond to ultraviolet phototherapy in the office in the same manner as we use it for severe psoriasis. The duration of suffering from lichen planus may last for months to 5 years, with an average of 2 years.
Oral Lichen Planus
Lichen planus of the oral cavity affects more women than men (about 2 to 1), and the average age of onset is older than for skin (about 52 years), suggesting that there may be immunological differences between the two different sites. However, the biopsy findings and immunological stains are nearly identical in skin and mucous membranes. Any part of the oral cavity may be affected by lichen planus, but the most common areas are the
inside of the cheeks, tongue, and gums. When there is particularly severe redness, swelling and bleeding of the gums due to lichen planus in a woman, there is about a 20% chance of severe genital involvement as well. In severe cases affecting the roof of the mouth or back of throat, swallowing may become impaired due to involvement of the esophagus.
The lesions of oral lichen planus are more varied in appearance than on skin. For example, the most common type of lichen consists of fine white lines (striae) and does not cause any symptoms. When we see redness between the white lines, there is usually more burning or pain felt by the patient. Some lesions just show thin red patches, but the worst cases demonstrate widespread open erosions and ulcers in the mouth, making eating, drinking, even speaking, difficult if not impossible.
Treatments of Oral Lichen Planus
Based on the wide range of severity that is possible, treatments range from none to high doses of prednisone and other immunosuppressive drugs. For the typical moderate case of lichen planus with striae and redness and oral discomfort, we prescribe steroid rinses or dermatological gels which are very effective for symptoms. It has been shown that about 30% of oral lichen planus patients also have yeast (Candida) infections in their mouths. Therefore, we also prescribe an anti-yeast medicine to be used along with the steroid. These patients usually do well with treatment, and the doseage of medicines can usually be reduced, but constant maintenance is required because the disease relapses 90% of the time!
The more severe cases are of course more difficult to manage. The high potency internal drugs that suppress the immune system do significantly reduce the inflammation, pain, and allow healing to occur, but usually cannot induce a complete remission or cure. In addition, there are many potential risks and side-effects that require monitoring by the experienced physician. I will list some of the drugs used here for those who are interested, so that you may do further research or ask your own physician about: prednisone, acitretin, cyclosporine, mycophenolate mofetil, azathioprine, thalidomide.
Interesting Associations with Oral Lichen Planus
Naturally, patients with oral lichen planus may have lichen planus in other anatomic areas. Skin involvement occurs in about 15% of oral cases, and oral involvement may seen in up to 50% of skin cases. However, my experience managing over 1000 cases over the years has taught me that severe cases in one area have minimal to no involvement in the other area.
The association of hepatitis C virus infection with oral lichen planus is controversial. In the recent past, it was recommended to screen for the hepatitis C antibody and measure liver enzymes in patients with oral lichen planus. Now we understand that there is an association between hepatitis C and oral lichen planus in countries that have a high prevalence of hepatitis C infection such as Italy, Spain and Japan, but not in the US, UK, or Germany. I do not order these tests unless a case is particularly resistant to standard therapy.
Just as with skin lichen planus, many drugs have been implicated as the cause of oral lichen planus. This has been difficult to prove for a number of reasons, however, the non-steroidal anti-inflammatory drugs including naproxen, ibuprofen and many others as well as the ACE inhibitor class of blood pressure medicine (includes lisinopril) are still suspected.
There have been a number of oral cancers reported in association with oral lichen planus, usually of the longstanding severe inflammatory type. It is possible that the cancers developed as a result of chronic inflammation or due to other risk factors such as genetic, alcohol or tobacco abuse. Some of the cases did clearly show on biopsies evidence of a progression from lichen planus to pre-cancer to squamous cell carcinoma.
Therefore, we do recommend an oral exam at least every 6 months for cancer surveillance, stopping tobacco habit, and reducing alcohol intake.
Finally, one of the most interesting associations is the reaction to corroded dental metal fillings, especially large ones when the filling lies adjacent lichen planus lesions on the inside of the cheek or tongue, or the surrounding gum tissue. These patients are often sensitive to the mercury content of the silver amalgam filling. A special type of allergy patch testing can be done to demonstrate the reaction on the skin. In such positive cases, I advocate removal of the metal fillings and replaced with white resin material. In studies showing positive mercury patch tests, the rate of complete clearance has been 100% within months of the procedure! Unfortunately, this type of oral lichen planus accounts for only 1% of the cases.
More About Autoimmune Diseases:
Painful Oral Erosions and White Patches
Two Novel Treatments for Oral Lichen Planus Hold Promise