Lichen planus is a common chronic inflammatory disease of unknown etiology occurring in the skin, hair follicles, mucous membranes and fingernails. Its etiology and pathogenesis are still inconclusive, there are autoimmune, genetic, infection, psychoneurological, drug, chronic lesion, metabolic and endocrine theories.
1.Immunological mechanism: lichen planus is cell-mediated immune reaction mainly, secondary and accompanying humoral immunity.
2, genetic: 1-2% have family history, even up to 10.7%, often acute pancytopenia, early onset, about 40% before 20 years of age.
3.Infection: Hepatitis C virus has been confirmed to be related to it.
4.Psychoneurosis: Lichen planus usually develops or worsens after mental tension, anxiety and depression, and 10% of cases have mental tension factors at the onset.
5, drugs: sulfonamides, gold or mercury agents, streptomycin, penicillamine, chlorosulfonylurea, toluenesulfonylurea and chlorothiazide. Oral flat moss 87% and amalgam filler mercury related.
6, and some diseases related: abnormal liver enzymes, primary biliary cirrhosis, diabetes and other immune diseases such as baldness, vitiligo, aspergillosis, etc. can be combined with lichen planus.