Lichen planus is a chronic skin condition. It causes itchy, flat, scaly patches on the wrists, legs, trunk, or genitals. It can also affect the inside of the mouth and vagina. There it resembles a white spider web.
The signs and symptoms of lichen planus vary depending on the areas affected. Typical signs and symptoms include:
- Purplish, flat-topped bumps, most often on the inner forearm, wrist or ankle, but sometimes on the external genitals
- Blisters that may break to form scabs or crusts
- Lacy white patches in the mouth — inside the cheeks or on the gums, lips or tongue
- Painful oral or vaginal ulcers
- Hair loss and scalp discoloration
- Nail damage or loss
- Biopsy. Your doctor removes a small piece of affected tissue for examination under a microscope. The tissue is analyzed to determine whether it has the cell patterns characteristic of lichen planus.
- Hepatitis C test. You may have your blood drawn to test for hepatitis C, which is a possible trigger for lichen planus.
- Allergy tests. Your doctor may refer you to an allergy specialist (allergist) or dermatologist for skin patch testing to identify agents to which you may be allergic and that may act as triggers for your condition.
Causes and risk factors?
Lichen planus develops when your body attacks your skin or mucous membrane cells by mistake. Doctors are not sure why this happens.
Lichen planus can occur in anyone at any age, but there are certain factors that make some people more likely to develop the condition. The skin form of lichen planus occurs in men and women equally, but women are twice as likely to get the oral form. It is very rare in children and older adults. It is most common in middle-aged people.
Other risk factors include having family members who’ve had lichen planus, having a viral disease like hepatitis C, or being exposed to certain chemicals that act as allergens. These allergens may include:
- iodide compounds
- certain kinds of dyes
Anytime you see or feel a rash on your skin or lesions in your mouth or on your genitals, you should see your doctor as soon as possible. Your primary care doctor may send you to a dermatologist if a diagnosis of lichen planus is not obvious, or if your symptoms are making you very uncomfortable.
Your primary care doctor or dermatologist may be able to tell that you have lichen planus simply by looking at your rash. To confirm the diagnosis, you may need further tests.
Tests could include a biopsy, which means taking a small sample of your skin cells to view under a microscope, or an allergy test to find out if you are having an allergic reaction. If your doctor suspects the underlying cause is an infection, you may need to have a test for hepatitis C.