- Mild to severe pruritus.
- Small polygonal, violaceous, flat topped, papules.
- The surface is transparent with a network of fine white striations (criss-cross lines).
- These lines are called “Wickham’s striae”
- These papules are widespread as clusters or coalesce into large plaques.
- Koebner’s phenomenon is commonly seen. Development of lesions along the lines of trauma over the normal skin.
- Common sites – flexor surface of wrists, forearms, hands, legs, neck and sacral areas.
- Other sites – oral mucosa, genitalia, scalp and nails.
Lichen planus represents:
- T-cell mediated autoimmune damage to basal keratinocytes.
- An increased association with other autoimmune disorders like ulcerative colitis, myasthenia gravis, lupus erythematosus, alopecia areata and diabetes.
- Exact nature of LP antigen is unknown.
- Increased frequency of HLA-B27, HLA-B51,HLA-BW57,HLA-DR1,HLA-DR4,HLA-DR6.
- In genetically predisposed person, the antigen can be self peptide or various exogenous agents like drugs, contact allergens, viruses or bacteria and mechanical trauma.
- Viruses – Hepatitis C (HCV)-Common in oral LP
- Human herpes virus (HHV-6)
- Vaccinations – HBV, Killed influenza, MMR,DPT
- Helicobacter. pylori
- Contact allergens – dental amalgams(mercury),copper and gold
- Incidence – 0.2% - 1%
- No racial predilection
- Seen in all age groups and both sexes
- More common in 30-60 years age group
- Familial cases are reported
