Lichen Planus

Lichen Planus (LP) is a chronic inflammatory condition affecting the skin, mucous membranes, hair follicles, and nails. While less common in children than adults, pediatric LP presents unique diagnostic and therapeutic challenges.

Key Points:

• Peak age of onset in children: 7-14 years
• Autoimmune-mediated inflammatory condition
• Can affect multiple body sites simultaneously
• Often presents with characteristic purple, polygonal, pruritic papules
• May be associated with various systemic conditions

Immunological Mechanisms

• Cell-Mediated Immunity:
• T-cell mediated autoimmune response
• CD8+ cytotoxic T-cells predominate
• Increased Th1 cytokine profile
• Basement membrane disruption
• Key Mediators:
• TNF-α
• IFN-γ
• IL-12
• IL-2
• CXCL9/10/11

Triggering Factors

• Viral Infections:
• Hepatitis C virus
• Epstein-Barr virus
• Human herpesvirus 7
• Other Triggers:
• Medications
• Dental materials
• Vaccinations
• Physical trauma (Koebner phenomenon)
• Stress

Classic Cutaneous Features

• Primary Lesions:
• Flat-topped papules
• Violaceous color
• Polygonal shape
• Wickham's striae (white reticular pattern)
• Size: 2-10mm
• Distribution:
• Flexor surfaces of wrists
• Forearms
• Legs
• Trunk
• Lumbar region
• Ankles

Mucosal Involvement

• Oral Manifestations:
• Reticular pattern
• Erosive lesions
• Plaque-like lesions
• Atrophic changes
• Bullous variants
• Genital Manifestations:
• Vulvar involvement
• Penile lesions
• Erosive variants

Nail Changes

• Longitudinal ridging
• Pterygium formation
• Thinning
• Subungual hyperkeratosis
• Complete nail destruction (rare)

Clinical Variants

1. Hypertrophic LP

• Thick, scaly plaques
• Predilection for lower extremities
• More resistant to treatment
• Risk of scarring

2. Atrophic LP

• Few well-demarcated papules
• Central atrophy
• Hyperpigmentation
• Common in children

3. Bullous LP

• Vesicles or bullae development
• Occurs within existing LP lesions
• May require systemic treatment

4. Actinic LP

• Sun-exposed areas
• Annular configuration
• More common in tropical regions

5. Linear LP

• Following Blaschko's lines
• More common in children
• May be confused with nevus

Diagnostic Approach

Clinical Diagnosis

• Detailed History:
• Onset and progression
• Associated symptoms
• Family history
• Medication history
• Triggering factors
• Physical Examination:
• Complete skin examination
• Oral cavity inspection
• Nail examination
• Genital examination when appropriate

Laboratory Studies

• Baseline Tests:
• Complete blood count
• Liver function tests
• Hepatitis C screening
• Autoimmune markers
• Histopathology:
• Interface dermatitis
• Hyperkeratosis
• Wedge-shaped hypergranulosis
• Band-like lymphocytic infiltrate
• Civatte bodies
• Direct Immunofluorescence:
• IgM deposits
• Fibrinogen deposits
• Shaggy fibrinogen deposits at BMZ

Treatment Strategy

First-Line Treatments

• Topical Therapy:
• Corticosteroids (Class I-II)
• Calcineurin inhibitors
• Retinoids
• Oral Medications:
• Antihistamines for pruritus
• Short-course systemic corticosteroids

Second-Line Treatments

• Systemic Agents:
• Oral retinoids
• Cyclosporine
• Methotrexate
• Mycophenolate mofetil
• Physical Treatments:
• Phototherapy (NB-UVB)
• PUVA (rarely in children)

Specific Variant Management

• Erosive LP:
• Intensive topical therapy
• Early systemic intervention
• Pain management
• Nail LP:
• Intralesional steroids
• Systemic therapy for severe cases

Potential Complications

• Physical Complications:
• Post-inflammatory hyperpigmentation
• Scarring
• Permanent nail dystrophy
• Oral pain and dysfunction
• Genital scarring
• Psychosocial Impact:
• Depression
• Anxiety
• Social withdrawal
• Impact on quality of life
• Long-term Concerns:
• Risk of malignant transformation (rare)
• Growth disturbance in nail variants
• Dental complications in oral LP

Prognostic Factors

• Disease Course:
• Usually self-limiting (12-18 months)
• Can be chronic in some variants
• Mucosal disease often more persistent
• Monitoring Requirements:
• Regular follow-up visits
• Photography for progression
• Quality of life assessment
• Screening for complications

Long-term Follow-up

• Regular monitoring of:
• Disease activity
• Treatment response
• Side effects of medications
• Psychological well-being