Clinical Overview

Lichen planus is a chronic autoimmune inflammatory disorder characterized by purple, polygonal, flat-topped (planar) papules with distinctive white lacy surface pattern (Wickham striae). This cutaneous condition frequently involves mucous membranes (oral in 50% of cases) and can progress to erosive variants with significant morbidity. Histologically, it shows lichenoid tissue reaction (saw-tooth acanthosis with basal cell apoptosis), establishing autoimmune cytotoxic destruction of keratinocytes and mucosal epithelium.

Epidemiology

Lichen planus affects 0.5-1% population, with peak incidence 40-60 years. Female predominance 1.5:1. Cutaneous-only disease in 50%, oral-only in 25%, both cutaneous and oral in 25%. Risk factors: hepatitis C infection (2-5 fold increased prevalence, particularly in endemic regions), hepatitis B, autoimmune thyroid disease, systemic lupus erythematosus, HIV infection. Medications trigger lichen planus reaction: beta-blockers (10-15% of LP patients), NSAIDs, antimalarials, thiazide diuretics, ACE inhibitors. Oral lichen planus carries malignancy risk: 0.5-5% progress to oral squamous cell carcinoma over 5-10 years, with highest risk in erosive and atrophic variants (2-3 fold higher). Cutaneous lichen planus rarely (<1%) undergoes malignant transformation; however, anogenital involvement increases cancer risk.

Pathophysiology

Lichen planus represents T-cell mediated autoimmune reaction against oral/cutaneous epithelium. CD8+ cytotoxic T lymphocytes recognize epithelial antigens (possibly cross-reactive with hepatitis C virus or other pathogens) and migrate to basal layer, destroying keratinocytes through FasL-induced apoptosis. HLA-A3 and HLA-B35 alleles associated with LP development, suggesting antigen presentation-dependent mechanism. Increased IgM and IgG antibodies against oral epithelial antigens detected in 25-50% of oral LP patients, though direct pathogenic role remains unclear. Th1/Th17 imbalance generates IL-17A, IL-22, TNF-alpha, and IFN-gamma perpetuating basal epithelial inflammation. Erosive LP characterized by more pronounced CD8+ infiltrate and enhanced protease activity (MMP-9, neutrophil elastase) driving epithelial ulceration and mucosal barrier breakdown.

Clinical Presentation

Cutaneous LP: purple, polygonal, flat-topped papules 1-5mm diameter with characteristic Wickham striae (white lacy/reticulate pattern on surface). Distribution: flexural wrists, forearms, lower legs, genitals, trunk. Oral LP: white lacy reticular pattern on buccal mucosa, tongue, and hard palate (reticular variant—most common); erythematous patches (atrophic variant); erosions/ulcerations (erosive variant—most severe, 5% of oral LP). Pruritus moderate to severe, particularly on lower extremities. Nail involvement in 10%: thinning, longitudinal ridging, pterygium formation (scarring), onycholysis. Mucosal involvement produces pain with hot/spicy foods, difficulty wearing dentures, altered taste. Erosive oral LP causes bleeding, impaired function, potential secondary infection. Spontaneous remission rate 10-20% within 1-2 years; however, 80-90% have persistent or recurrent disease.

Diagnosis

Diagnosis primarily clinical based on characteristic purple polygonal papules with Wickham striae. Dermoscopy/oral examination reveals reticular white pattern pathognomonic for LP. Histopathology shows: saw-tooth (bandlike) acanthosis, basal cell apoptosis, dense lymphocytic infiltrate in subepithelial zone. Immunofluorescence demonstrates IgM deposition at dermal-epidermal junction (fibrinogen pattern), though non-specific. Hepatitis C serology mandatory in all LP patients (2-5% seroprevalence with variation by geography/risk). Thyroid function testing and anti-TPO antibodies recommended (autoimmune thyroid disease comorbidity). Patch testing indicated if drug-induced LP suspected (beta-blockers, NSAIDs, etc.). Oral biopsy essential for erosive oral variants to exclude malignancy and confirm diagnosis.

Treatment Algorithm

Localized Cutaneous Lichen Planus: Potent topical corticosteroids (clobetasol propionate 0.05% cream/ointment twice daily) applied directly to lesions. Efficacy 60-70% with 8-12 week therapy producing lesion flattening and pruritus relief. Intralesional corticosteroid injection (triamcinolone acetonide 5-10mg/mL, 0.1-0.3mL per lesion) highly effective for recalcitrant papules, producing 80% resolution within 2-4 weeks. Repeat injections monthly as needed. Topical retinoids: tretinoin 0.05-0.1% nightly, adapalene 0.1% accelerate keratinocyte differentiation, reducing inflammation; slower onset (4-6 weeks) but good long-term remission rates. Tacrolimus 0.1% ointment alternative for face/neck (steroid-sparing).

Extensive Cutaneous or Oral Lichen Planus: Systemic corticosteroids: prednisolone 0.5-1 mg/kg/day for 2-4 weeks with slow 4-8 week taper; effective in 70% of erosive oral LP. Short-course therapy preferred to minimize long-term toxicity. Oral retinoids: acitretin 25-50mg daily effective for mucocutaneous LP; 60% response within 8-12 weeks. Teratogenicity requires contraception in reproductive females. Requires lipid monitoring (hypertriglyceridemia in 60%). Methotrexate 7.5-15mg weekly: 60-70% response rate, longer onset (8-12 weeks), requires CBC/liver/renal monitoring. Mycophenolate mofetil 1-1.5g twice daily: emerging agent with favorable immunosuppressive profile, 50-60% response rates in uncontrolled series.

Erosive Oral Lichen Planus: First-line: topical corticosteroid gel/paste (triamcinolone 0.1% paste or fluocinonide 0.05%) applied directly to erosions 3-4 times daily after meals. Add topical anesthetic (viscous lidocaine 2%) for pain management. Response 60-70% within 4 weeks. Oral rinses: prednisolone 5-7.5mg dispersed in 20mL saline, rinse for 2 minutes 3-4 times daily, swish then spit (local steroid application with minimal systemic absorption). Add oral antifungal (clotrimazole 10mg troche 5 times daily) due to Candida superinfection risk (develops in 40% of erosive cases). Systemic corticosteroids: prednisolone 0.5-1 mg/kg/day for 2-4 weeks essential for moderate-severe erosive disease; 70% achieve significant healing within 4 weeks. Alternative: cyclosporine 5-10 mg/kg/day (requires renal/BP monitoring) for steroid-refractory cases or long-term control.

Refractory Lichen Planus: TNF-inhibitors (etanercept 50mg SC twice weekly, adalimumab 40mg SC every 2 weeks): emerging evidence supports efficacy in refractory cutaneous and oral LP (50-70% response); mechanism via TNF-alpha suppression reducing CD8+ infiltration. JAK inhibitors (ruxolitinib, baricitinib) in early trials show promise for refractory LP (off-label). Apremilast (phosphodiesterase-4 inhibitor) 30mg twice daily: 40-50% response in uncontrolled studies.

Prognosis

Lichen planus is chronic with variable natural history: 10-20% spontaneous remission within 1-2 years; 80% persistent or recurrent requiring ongoing therapy. Cutaneous disease generally favorable: 70% respond to topical corticosteroids alone. Oral LP more treatment-resistant: 40-50% achieve complete remission, 30-40% partial remission, 20-30% refractory. Erosive variants carry highest morbidity and malignancy risk (0.5-5% lifetime oral SCC risk). Early aggressive systemic therapy reduces scarring risk and prevents morphea/lichen sclerosus-like sequelae. Baseline and annual oral examination essential for malignancy surveillance.

When to See a Dermatologist

Refer for diagnostic confirmation, erosive disease, extensive involvement, systemic therapy consideration, or oral variants requiring monitoring. Coordinate with oral medicine specialist for erosive oral LP. Annual surveillance for malignancy in erosive variants essential.

Frequently Asked Questions

Q: Is lichen planus contagious?
A: No, lichen planus is not contagious. It is an autoimmune condition where your body's immune system attacks skin/mucosal cells. Close contact, sharing utensils, or sexual contact cannot transmit the disease.

Q: What causes lichen planus?
A: Cause remains unclear but involves immune dysregulation attacking epithelial cells. Hepatitis C infection, medications (beta-blockers, NSAIDs), or possible cross-reactive viral antigens may trigger disease in genetically predisposed individuals. Stress may exacerbate flares.

Q: Will it turn into cancer?
A: Cutaneous lichen planus rarely becomes cancer (<1%). Oral lichen planus, particularly erosive forms, carries 0.5-5% lifetime risk of squamous cell carcinoma. Regular oral exams by dermatology or oral medicine important for early detection if concerning changes develop.

Q: How long does treatment take to work?
A: Topical corticosteroids provide relief within 1-2 weeks but require 8-12 weeks for lesion flattening. Systemic therapy requires 4-8 weeks minimum. Retinoids take 6-8 weeks. Patience and adherence essential; do not discontinue prematurely.

References

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