What are the diagnosis and treatment options for Verruca plana on the face?

Diagnosis and Treatment of Verruca Plana on the Face

For facial verruca plana (flat warts), photodynamic therapy with 10% aminolevulinic acid is the most effective treatment, showing up to 94% clearance rates while minimizing post-treatment hyperpigmentation risk. 1

Diagnosis

Verruca plana (flat warts) are benign epithelial proliferations caused by human papillomavirus (HPV) that appear as:

• Small, flat-topped papules (1-5mm)
• Flesh-colored or slightly hyperpigmented
• Smooth surface without the hyperkeratotic appearance of common warts
• Often multiple and grouped together
• Commonly found on the face, especially forehead, temples, and cheeks

Differential diagnosis may include:

• Seborrheic keratosis (can be distinguished using confocal laser scanning microscopy) 2
• Molluscum contagiosum
• Lichen planus

Treatment Options

First-line Treatments:

1. Topical Salicylic Acid (15-26%)

   • Mechanism: Promotes exfoliation and acts as an irritant
   • Application: Daily after removing keratin layer
   • Duration: 3-4 months
   • Evidence: Strongest evidence base (Strength of recommendation A) 1, 3
   • Caution: Use lower concentrations on facial skin to avoid irritation

2. Topical Retinoids

   • Mechanism: Promotes cell turnover and exfoliation
   • Application: Once daily at bedtime
   • Duration: 8-12 weeks
   • Note: Often used as first-line for facial flat warts due to good tolerability

Second-line Treatments:

1. 5-Fluorouracil (5%)

   • Mechanism: Blocks DNA synthesis in rapidly dividing cells
   • Application: Once or twice daily under occlusion
   • Duration: 3-5 weeks
   • Efficacy: 82% clearance rate for facial verruca plana 4
   • Side effects: Hyperpigmentation (73%), erythema (45%), erosion (45%) 4

2. Imiquimod (5%)

   • Mechanism: Immune response modifier stimulating interferon and cytokine production
   • Application: 2-3 times weekly
   • Duration: Up to 16 weeks
   • Note: Well-tolerated on facial skin compared to more destructive methods 5

Advanced Treatments for Resistant Cases:

1. Photodynamic Therapy (PDT)

   • Mechanism: Photosensitizer applied to lesions followed by light exposure
   • Protocol: 10% aminolevulinic acid (reduced from 20% for facial application) 1
   • Efficacy: Up to 94% clearance for facial verruca plana 1
   • Advantage: Reduced risk of post-treatment hyperpigmentation with lower concentration

2. Cryotherapy

   • Mechanism: Tissue destruction through freezing
   • Protocol: Light application with liquid nitrogen
   • Caution: Risk of hypopigmentation or scarring on facial skin
   • Often combined with other treatments (e.g., with imiquimod) 5

3. Laser Therapy

   • Options: YAG lasers, pulsed dye laser
   • Best for: Recalcitrant cases not responding to other treatments
   • Caution: Higher risk of scarring on facial skin 6

Novel Approach:

1. HPV Vaccination
   • Mechanism: May stimulate immune response against existing HPV infection
   • Evidence: Case report of complete resolution of extensive facial verruca plana following first dose of nonavalent HPV vaccine 7
   • Consideration: May be considered in adolescents who are candidates for HPV vaccination

Treatment Algorithm

1. For limited facial verruca plana (few lesions):

   • Start with topical salicylic acid (10-15%) or topical retinoid
   • If no response after 8 weeks, switch to 5% imiquimod 3 times weekly

2. For extensive facial verruca plana (multiple lesions):

   • Consider photodynamic therapy with 10% aminolevulinic acid
   • Alternative: 5% 5-fluorouracil applied once daily for 3-5 weeks

3. For resistant cases:

   • Combination therapy: Cryotherapy followed by imiquimod
   • Consider laser therapy for persistent lesions

Important Considerations

• Facial skin requires gentler treatment approaches than other body areas to minimize scarring and pigmentation changes
• Reduce concentration of treatments when applying to facial skin (e.g., 10% instead of 20% for PDT) 1
• Monitor for hyperpigmentation, which is a common side effect of many treatments
• Treatment duration is typically longer for verruca plana than for common warts
• Consider the psychological impact of facial warts and prioritize treatments with lower risk of scarring

Prevention

• Avoid sharing personal items like towels and razors
• Avoid scratching or picking at lesions to prevent autoinoculation
• Consider HPV vaccination in appropriate age groups