Diagnosis

Your doctor makes a diagnosis of lichen planus based on your symptoms, your medical history, a physical examination and, if necessary, the results of lab tests. These tests may include:

• 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 to find out if you're allergic to something that can trigger lichen planus.

Other tests may be needed if your doctor suspects you have any of the several variations of lichen planus, such as the type that affects the esophagus, genitals, ears or mouth.