What are the diagnostic criteria and treatment options for lichen planus nail (lichen planus of the nail)?

Diagnostic Criteria and Treatment for Lichen Planus of the Nail

Nail lichen planus requires prompt diagnosis and early treatment with intralesional triamcinolone acetonide as first-line therapy to prevent permanent nail destruction and scarring.

Diagnostic Criteria for Nail Lichen Planus

Nail lichen planus (NLP) affects approximately 10% of patients with lichen planus and can occur in isolation without skin or mucosal involvement. Accurate diagnosis is crucial as it can mimic other nail disorders, particularly onychomycosis.

Key Clinical Features:

• Nail Matrix Involvement (present in 85-91% of cases) 1, 2:

  • Thinning of the nail plate
  • Longitudinal ridging (onychorrhexis)
  • Pterygium formation (most characteristic sign)
  • Trachyonychia (rough nail surface)

• Nail Bed Involvement:

  • Subungual hyperkeratosis
  • Onycholysis (separation of nail from nail bed)
  • Longitudinal melanonychia (brown/black lines)

• Other Distinguishing Features 3:

  • Dorsal pterygium (extension of the proximal nail fold onto the nail plate)
  • Lateral nail plate thinning
  • Unlike onychomycosis, the nail surface does not become soft and friable

Diagnostic Workup:

1. Nail Biopsy - Gold standard for diagnosis 1:

   • Contributory in 90% of cases
   • Often requires two specimens for accurate diagnosis
   • Relatively safe procedure with minimal scarring risk

2. Histopathological Findings:

   • Lichenoid infiltrate
   • Hyperkeratosis
   • Saw-tooth acanthosis
   • Degeneration of the basal layer

3. Differential Diagnosis 3:

   • Onychomycosis (rule out with KOH preparation, fungal culture, or PCR)
   • Psoriasis
   • Trauma-induced nail dystrophy
   • Darier disease
   • Yellow nail syndrome

Treatment Algorithm for Nail Lichen Planus

First-Line Therapy:

• Intralesional triamcinolone acetonide (5-10 mg/cc) 3, 4:
  • Inject into the proximal nail fold for matrix involvement
  • Most effective when started early
  • Typically requires multiple injections (improvement often seen after 3 injections) 2
  • Particularly effective for cases with <3 nails involved

Second-Line Therapies:

• Systemic corticosteroids 1:

  • Used in more extensive disease (>3 nails involved)
  • Can be combined with intralesional injections for enhanced effect

• Oral retinoids 3, 4:

  • Acitretin (0.2-0.4 mg/kg daily)
  • Particularly useful for cases with >3 nails involved

Third-Line/Severe Disease Options:

• Immunosuppressive agents 3:
  • Cyclosporine
  • Azathioprine
  • IL-17 inhibitors
  • Tofacitinib

Topical Treatments:

• Topical high-potency corticosteroids:
  • Less effective than intralesional or systemic treatments
  • May cause long-term side effects
  • Can be used as adjunctive therapy

Prognosis and Follow-up

The prognosis of nail lichen planus is generally poor with a high rate of relapses and permanent damage to the nail unit 1. Early diagnosis and treatment are crucial to prevent irreversible nail destruction.

• Regular follow-up is essential to monitor response to treatment
• Permanent damage occurs in approximately 4-12% of patients 5
• Children may develop aesthetically unacceptable nail scarring if not treated early 2

Important Considerations

• Stress may be a triggering factor in 20% of patients 2
• Pediatric cases represent a significant proportion (40% in some series) 2
• Complete nail involvement (20 nails) occurs in approximately 55% of patients 2
• Severe manifestations like pterygium or anonychia occur in 25% of cases 2

Early diagnosis and aggressive treatment are essential to prevent permanent nail destruction and preserve nail function and appearance, especially in pediatric patients where the risk of scarring is high.