Lichen Planus

Lichen planus is a chronic immune-mediated inflammatory disorder affecting the skin, mucous membranes, hair follicles, and nails. It is characterized by intensely pruritic violaceous papules and plaques and may follow a prolonged relapsing course.

The disease is mediated by T-cell–driven autoimmune attack against basal keratinocytes, leading to destruction of the epidermal basal layer.

It commonly affects adults between 30–60 years, and may be associated with certain medications, infections (notably hepatitis C), and stress.

Etiology and Risk Factors

Idiopathic (most common)

Exact cause unknown

Drug-induced (Lichenoid drug eruption)

Common triggers include:

• Antimalarials

• Thiazide diuretics

• NSAIDs

• Beta-blockers

• ACE inhibitors

• Gold salts

Associated Conditions

• Hepatitis C infection

• Autoimmune diseases

• Psychological stress

• Dental amalgam reactions (oral lichen planus)

Pathophysiology

• Cytotoxic CD8+ T-cells attack basal keratinocytes

• Degeneration of basal cell layer occurs

• Hyperkeratosis develops

• Leads to characteristic purple polygonal papules

Classic description:“6 Ps” of Lichen Planus

• Pruritic

• Purple

• Polygonal

• Planar

• Papules

• Plaques

Clinical Features

Cutaneous Lichen Planus

• Violaceous shiny flat-topped papules

• Fine white lines (Wickham striae)

• Lesions coalesce into plaques

• Extremely itchy

Distribution

• Flexor wrists

• Forearms

• Inner thighs

• Sacral area

• Ankles

Post-Inflammatory Changes

• Hyperpigmentation common (especially darker skin)

Oral Lichen Planus

• Reticular white lacy patches

• Painful erosions

• Burning sensation with spicy food

Hair Involvement (Lichen Planopilaris)

• Patchy hair loss

• Permanent scarring alopecia

Nail Involvement

• Longitudinal ridging

• Thinning

• Pterygium formation

• Nail loss (severe cases)

Signs & Symptoms

• Violaceous shiny flat-topped papules

• Coalescing scaly plaques

• Severe itching

• Distribution on inner wrists, arms, thighs and sacral area

• Post-inflammatory hyperpigmentation

• Possible scarring alopecia (lichen planopilaris)

Diagnostic Criteria

Clinical diagnosis based on:

• Classic purple polygonal papules

• Flexural distribution

• Intense pruritus

• Post-inflammatory pigmentation

• Possible hair follicle destruction

Skin biopsy confirms diagnosis if uncertain.

Investigations

Usually clinical diagnosis, but may include:

• Skin biopsy (saw-tooth lymphocytic infiltrate)

• Hepatitis C screening

• Liver function tests

• Direct immunofluorescence (if atypical)

For oral lesions:

• Biopsy to rule out malignancy in chronic erosive disease

Treatment

Treatment aims to relieve itching, suppress inflammation, and prevent scarring.

Non-Pharmacological Treatment

• Avoid scratching

• Stress reduction

• Avoid triggering drugs

• Gentle skin care

• Avoid irritating soaps

• Maintain oral hygiene (oral LP)

• Avoid spicy or acidic foods (oral involvement)

Pharmacological Treatment

Mild to Moderate Disease

• Chlorpheniramine 4 mg orally every 6 hours for 2 weeks

AND

• Betamethasone valerate ointment 0.1% twice daily for 2–4 weeks

OR

• Clobetasol propionate ointment 0.05%–0.1% twice daily for 2–4 weeks

Severe Disease

Refer to specialist for:

• Systemic corticosteroids

• Occlusive topical steroid therapy

• Retinoids

• Phototherapy

Oral Lichen Planus (Painful)

• Topical high potency steroid gel

• Topical anesthetic mouthwash

Complications

• Persistent hyperpigmentation

• Permanent scarring alopecia

• Nail dystrophy

• Secondary infection

• Squamous cell carcinoma (rare, oral erosive type)

Prognosis

• Cutaneous disease: resolves within 1–2 years in many patients

• Oral disease: chronic and recurrent

• Pigmentation may persist long after lesions heal

Prevention

• Avoid triggering medications

• Early treatment of lesions

• Manage stress

• Regular follow-up for oral lesions

• Good skin and oral hygiene