How is pathophysiology of LP?

• The pathogenesis of lichen planus remains unclear, it appears to be an autoimmune disease • The basal keratinocyte degeneration observed in LP is attributed to cytotoxic CD8+ T lymphocytes, which are the major component of the infiltrates located within the epithelium and adjacent to damaged keratinocytes • The triggering antigen is not known • The existence of rare cases of familial lichen planus and the over representation of certain HLA haplotypes (HLA-DR1 in cutaneous LP) suggest that genetic factors have a role in susceptibility to this disease • Several autoimmune disorders, particularly alopecia areata and ulcerative colitis have been reported to occur more frequently in patients with lichen planus than in control populations • There is a significant association between LP and infection with hepatitis C virus (HCV)