What are the guideline treatments for periungual warts?

Guideline Treatment for Periungual Warts

For periungual warts, start with topical salicylic acid (15-26%) as first-line therapy, applied daily after paring down the warts for 3-4 months; if this fails, switch to cryotherapy with liquid nitrogen every 1-2 weeks, and for refractory cases consider intralesional bleomycin or photodynamic therapy combined with CO2 fractional laser. 1, 2, 3

First-Line Treatment: Salicylic Acid

• Salicylic acid (15-26%) is the recommended first-line treatment for periungual warts based on the British Association of Dermatologists guidelines, which give it an "A" strength recommendation for hand warts due to strong evidence and best safety profile. 1, 2

• Apply salicylic acid daily after carefully paring or debriding the wart to remove the thick keratin layer that blocks penetration. 2

• Continue treatment for 3-4 months before declaring failure, as periungual warts require prolonged therapy due to their location and thickness. 2

• Critical pitfall: Avoid damaging surrounding skin during paring, as this spreads the viral infection through autoinoculation to adjacent areas. 2

Second-Line Treatment: Cryotherapy

• If salicylic acid fails after 3 months, switch to cryotherapy with liquid nitrogen, which has a "B" strength recommendation from British guidelines for hand warts. 2

• Freeze the wart for 15-30 seconds and repeat treatments every 1-2 weeks. 2

• Continue for at least 3 months or six treatment sessions before changing approach. 2

• Cryotherapy is effective but requires proper training to avoid over- or under-treatment, which can lead to poor efficacy or complications. 1

Third-Line Options for Refractory Cases

Combination Therapy

• Combine salicylic acid with cryotherapy for warts not responding to monotherapy, as this has been shown to be more effective than salicylic acid alone. 2

Intralesional Bleomycin

• Intralesional bleomycin (0.1 U/mL) using translesional multipuncture technique is highly effective for refractory periungual warts, with 86.6% complete clearance after a single injection in one prospective study. 4

• This has a strength "C" recommendation from British guidelines as a third-line option. 2

• Inject after local anesthesia, with one to three treatments typically needed. 2

• Side effects are minimal at this low concentration (0.1 U/mL), with only localized moderate pain for 2-3 days reported in 60% of patients. 4

Photodynamic Therapy with Laser

• For highly resistant periungual warts, CO2 fractional laser followed by methyl-5-amino-laevulinic acid (MAL)-PDT achieved 90% complete clearance with no recurrence at 6 months in a cohort of 12 patients. 1

• Apply MAL for 3 hours, then use 50 J/cm² light irradiation for 15 minutes, with fortnightly treatments over 6 weeks. 1

• Prepare warts before PDT with curettage or keratolytic cream to enhance penetration of the photosensitizer. 1

Contact Immunotherapy

• Diphenylcyclopropenone (DPC) or squaric acid dibutylester (SADBE) can be used as third-line options with strength "C" recommendation, applied from twice weekly to every 3 weeks for 3-6 months. 2

Surgical Options

• Surgical removal by curettage, electrosurgery, or CO2 laser are widely used but lack high-quality evidence, with only level 3 evidence and strength "D" recommendation. 1

• These should be reserved for extensive or refractory disease that has failed multiple medical therapies. 1

• Warning: Surgical approaches risk permanent nail changes and scarring, which is particularly problematic in the periungual area. 3, 4

Treatment Algorithm Summary

1. Start: Salicylic acid 15-26% daily with paring for 3-4 months 2
2. If failure: Switch to cryotherapy every 1-2 weeks for 3 months 2
3. If still refractory: Consider combination therapy (salicylic acid + cryotherapy) OR intralesional bleomycin 0.1 U/mL 2, 4
4. For highly resistant cases: PDT with CO2 fractional laser or contact immunotherapy 1, 2

Key Pitfalls to Avoid

• Do not overtreat: Scarring in the form of persistent hypopigmentation, hyperpigmentation, or hypertrophic scars can occur if insufficient healing time between treatments. 2

• Change modality if no improvement after 3 provider-administered treatments or if warts haven't cleared after 6 treatments. 2

• Avoid aggressive destructive therapies initially, as periungual warts can cause permanent nail deformity if overtreated. 3

• Remember that definitive cure is not guaranteed by any therapy, and periungual warts can recur even after correct treatment. 3