Lichen planus !
Lichen planus is an immune skin condition with itchy, flat, purple bumps on the wrists and ankles. It can also affect the mouth, genitals and nails.
Updated 2026-11-01
Structures involved
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Why it happens
- Apoptosis: the intrinsic and extrinsic pathways
- Skin: epidermis layers, dermis, hypodermis
- Basement membrane
What it is
A chronic, T cell–mediated inflammatory disease of the skin, mucous membranes, hair and nails. Skin lesions are the classic purple, polygonal, pruritic, flat-topped papules; oral lichen planus shows white lacy (reticular) streaks.
Who gets it
Affects about 1% of adults, mostly aged 30–60. Oral lichen planus is more common in women. An association with hepatitis C virus infection has been reported, varying by region.
Causes
- Cytotoxic T cells attacking basal keratinocytes, likely against an altered self-antigen
- Hepatitis C virus infection is associated in some populations
- Lichenoid drug eruptions: beta-blockers, ACE inhibitors, thiazides, antimalarials, gold, NSAIDs
- Contact with dental amalgam in some oral lesions
Risk factors
- Middle age
- Hepatitis C infection
- Exposure to culprit drugs
- Other autoimmune diseases
Pathophysiology
CD8+ T cells accumulate at the dermo-epidermal junction and trigger apoptosis of basal keratinocytes. Histology shows a band-like lymphocytic infiltrate, saw-tooth rete ridges, hypergranulosis and colloid (Civatte) bodies. The thickened granular layer produces the white Wickham striae.
Classification
- Cutaneous (classic, hypertrophic, annular, linear, bullous)
- Oral (reticular, erosive, atrophic, plaque-like)
- Genital (vulvovaginal-gingival syndrome), nail and scalp (lichen planopilaris) forms
- Lichenoid drug eruption
Symptoms and signs
- The six Ps: purple, polygonal, pruritic, planar (flat-topped) papules and plaques
- Fine white lines on the surface (Wickham striae)
- Typical sites: flexor wrists, forearms, ankles, shins, lower back
- New lesions along scratch lines (Koebner phenomenon)
- Oral: white lacy streaks on the buccal mucosa, gums or tongue; painful erosions in erosive forms
- Nails: thinning, ridging, pterygium; scalp: scarring hair loss
Diagnosis
- Clinical
- Clinical recognition of the six Ps and Wickham striae; examine mouth, genitals, nails and scalp. Review medication history for lichenoid drug eruption.
- Tests
- Skin or mucosal biopsy (band-like lymphocytic infiltrate at the dermo-epidermal junction, Civatte bodies); direct immunofluorescence in uncertain cases. Hepatitis C serology is commonly checked.
- Imaging
- Not needed. Dermoscopy shows Wickham striae clearly.
Differential diagnosis
- Psoriasis (silvery scale, extensor surfaces)
- Lichenoid drug eruption
- Discoid lupus erythematosus
- Oral candidiasis and leukoplakia (oral lesions)
- Lichen sclerosus (genital lesions); secondary syphilis
Goal of treatment
Relieve itch and pain, speed resolution of skin lesions, control mucosal disease, and monitor oral and genital lesions for cancer; stop any culprit drug.
Treatment
- Medical
- High-potency topical corticosteroids are first-line for skin lesions; topical corticosteroids or calcineurin inhibitors for oral lesions.
- Medical
- Antihistamines for itch; intralesional corticosteroids for hypertrophic lesions.
- Medical
- Widespread or resistant disease: systemic corticosteroids for short periods, acitretin, methotrexate or other immunosuppressants.
- Procedure
- Narrowband UVB phototherapy for extensive cutaneous disease.
- Follow-up
- Regular review of oral and genital lesions for malignant change; good oral hygiene and dental care; avoid tobacco and alcohol.
Complications
- Post-inflammatory hyperpigmentation, prominent in darker skin
- Squamous cell carcinoma in chronic erosive oral or genital lesions
- Scarring alopecia and permanent nail loss
- Vulvovaginal or oesophageal stenosis
Prognosis
Cutaneous lichen planus usually resolves within 1–2 years, often leaving pigmentation. Oral and genital forms are chronic and relapsing and need long-term follow-up because of the small cancer risk.
Test yourself
Think of the answer, then tap the question to see it.
What are the six Ps of lichen planus?
Purple, polygonal, pruritic, planar (flat-topped) papules and plaques.
What are Wickham striae?
Fine white lacy lines on the surface of lichen planus lesions, also seen in the mouth.
Which viral infection is associated with lichen planus?
Hepatitis C virus infection.
What is the typical histology of lichen planus?
A band-like lymphocytic infiltrate at the dermo-epidermal junction with saw-tooth rete ridges and Civatte bodies.
Which malignancy can develop in chronic erosive oral lichen planus?
Oral squamous cell carcinoma.
Related conditions
- Viral hepatitis
- Psoriasis
- Discoid lupus erythematosus
- Head and neck squamous cell carcinoma (oral cavity and oropharynx, HPV)
- Vulvar lichen sclerosus and vulvar cancer
- Cutaneous and mucocutaneous candidiasis
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Lichen planus (MedlinePlus, US National Library of Medicine, 2026).
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