What is the recommended treatment for flat warts in a patient taking systemic isotretinoin (13-cis-retinoic acid)?

Treatment of Flat Warts in Patients Taking Systemic Isotretinoin

For patients taking systemic isotretinoin, low-dose oral isotretinoin (0.1-0.2 mg/kg/day) is the recommended treatment for flat warts, as it has shown complete clearance of recalcitrant facial flat warts with minimal side effects. 1, 2

Treatment Considerations with Isotretinoin

Skin Changes During Isotretinoin Therapy

• Isotretinoin causes significant skin changes:
  • Increased skin fragility
  • Decreased barrier function
  • Delayed wound healing
  • Increased risk of skin irritation
  • Higher rates of S. aureus colonization 3

First-Line Treatment Options

Low-Dose Oral Isotretinoin

• Dosage: 0.1-0.2 mg/kg/day for 3 months 2
• Benefits:
  • Complete clearance demonstrated in clinical trials 1
  • Effective for recalcitrant cases
  • Minimal additional side effects beyond those already experienced from acne treatment
  • Long-term remission noted for up to 3 years 2
• Monitoring:
  • Continue regular liver function tests, serum cholesterol, and triglycerides monitoring already in place for acne treatment 4

Alternative Treatment Options

Topical Treatments (Use with Caution)

• Glycolic acid 5%:

  • Well-tolerated in facial plane warts
  • Cleared all cases in a small study without producing scarring 4
  • Lower risk of irritation than salicylic acid

• Low-concentration salicylic acid (2%):

  • Use with extreme caution due to potential for increased irritation
  • Consider only for small, isolated lesions
  • Avoid occlusion 4, 3

Cryotherapy

• Use milder freeze technique than for common warts
• Caution: May cause hypopigmentation or hyperpigmentation, especially in darker skin types 4
• Avoid aggressive treatment due to delayed healing with isotretinoin

Treatment Algorithm

1. Assessment:

   • Determine extent and location of flat warts
   • Consider duration of isotretinoin therapy and current dose

2. Treatment Selection:

   • Extensive or facial flat warts: Low-dose oral isotretinoin (0.1-0.2 mg/kg/day)
   • Limited, non-facial warts: Consider glycolic acid 5% or very mild cryotherapy

3. Follow-up:

   • Monitor for 3 months
   • Assess for clearance and side effects

Special Considerations

Facial Flat Warts

• Require special attention due to higher risk of scarring
• Avoid salicylic acid paints which are contraindicated on the face 4
• Prioritize treatments with minimal risk of permanent scarring

Potential Pitfalls

• Avoid aggressive destructive treatments that may lead to scarring
• Remember that flat warts may resolve spontaneously (within 1-2 years in children, though can persist 5-10 years in adults) 3
• Higher concentrations of topical treatments may cause chemical burns, scarring, and discoloration

Evidence Quality

The most recent evidence from a 2015 double-blind, randomized, placebo-controlled trial demonstrated that isotretinoin is highly effective for recalcitrant facial flat warts, with complete clearance in all treated patients compared to no improvement in the placebo group 1. More recent case series have confirmed the efficacy of lower doses with fewer side effects 2, 5.