Lichen planus is a T cell-mediated autoimmune disease that causes a characteristic violaceous papular rash on the skin and white lesions in the mouth. It involves the skin, mucous membranes, legs, scalp, and genitalia. Patients typically present with itchy, polygonal papules that initially develop on flexures and later spread more widely. Lichen planus has no known cure but treatments include topical steroids for mild cases and oral steroids or immunosuppressants for more severe or widespread disease.

1. Lichen Planus

2. Definition
• “Dermatosis of unknown origin characterised by
typical violaceous papular eruption on
characteristic sites and white mucosal lesions.”
• (dermatosis means non-inflammatory lesion which
involves integumentary system)

4. Pathogenesis
• Lichen planus is a T cell-mediated autoimmune
disease, in which inflammatory cells attack an
unknown protein within skin and mucosal
keratinocytes.
• HLA-3 , HLA-5

5. Etiology
• Associated with other immune conditions e.g.
ulcerative colitis , alopecia areata , vitiligo etc .
• Genetic predisposition 1-2%
• Associated with hepatitis C virus infection.
• Koebner`s phenomena
• Drugs e.g. gold , quinine , arsenic , isoniazid ,
streptomycin , photocolor developer , dental
amalgam
• Complication of bone marrow transplant

6. Involves:
• Skin
• Mucous membrane
• Legs
• Scalp
• Genitalia

7. Patient presents with :
• Pin-point papules/ polygonal plaques
• Grouped /discrete
• Well-marked itching
• Initially , they develop on flexures and later
generalised eruption occurs .

8. 5Ps
Plane-
topped
purple
pruritic
polygon
al
papules

9. Common sites :
• Wrists and forearm
• Lumbar region
• Lower legs and ankles

10. Chronic lesions
Palms and soles :
• yellowish
• hyperkeratotic papules
Nail changes
• Thinning
• Longitudnal lines
• Pterygium(scar)

11. Wickham`s straie

12. Mucosal lesion
Network of white streaks characteristic

13. Colour changes
Early lesion Late lesion

14. Legs(develops into chronic hypertrophic)

15. Palms, soles

16. Lichen-planopilaris

17. Nails

18. Prognosis
• Acute attack clears in 6-9 months .
• Ordinary type 6-18 months .
• Hypertrophic types takes several years .

19. Diagnosis
• Clinically
• Biposy may be taken to confirm and look for
complication i.e SCC
• Patch test : in case of oral lesions to check for
mercury allergy .

20. Treatment
• Acute : topical steroids , antihistamine .
• Hypertrophic : intralesional steroid , oral
antihistamine .
• Severe local/systemic : oral prednisolone

21. Other options for widespread disease :
• Narrow-band or broadband UV-B therapy
• Psoralen with UV-A (PUVA) therapy
• Azathioprine
• cyclosporin