What is the appropriate treatment for a 10-year-old male with multiple non-healing plantar warts, one of which shows signs of possible infection, and a history of birthmarks and hyperpigmentation, who experiences pain upon contact and after physical activity?

Treatment of Plantar Warts in a 10-Year-Old with Signs of Infection

Immediate Management: Address the Infected Wart First

The wart with surrounding erythema and warmth requires immediate evaluation for secondary bacterial infection before proceeding with destructive wart treatments. If infection is confirmed, initiate appropriate antibiotic therapy and defer aggressive wart treatment until the infection resolves 1. Treating an infected wart with destructive modalities risks spreading bacteria and worsening the infection.

Key Clinical Considerations:

• Do not apply salicylic acid, cryotherapy, or other destructive treatments to inflamed or infected areas until any secondary infection has completely resolved 2
• The patient's pain level (crying after physical activity) indicates significant functional impairment, making watchful waiting inappropriate despite the relatively short duration (one month) 1
• The birthmarks and hyperpigmentation mentioned are likely unrelated to the wart treatment but document them for completeness

First-Line Treatment Protocol (After Infection Resolves)

Start with salicylic acid 15-26% applied daily after proper debridement, with occlusion, for a full 3-4 months. This represents the highest quality evidence (Level 1+, Grade A recommendation) for plantar wart treatment 1, 2.

Proper Application Technique:

• Soak the warts in warm water for 5-10 minutes to soften the thickened keratin layer 2
• Debride/pare down each wart using a disposable emery board or pumice stone before each application, removing only the white thickened keratin 1, 2
• Stop paring immediately if pinpoint bleeding occurs, as this indicates reaching the dermal papillae 2
• Apply salicylic acid only to the wart surface, avoiding surrounding normal skin 1
• Cover with an occlusive dressing (bandage or tape) to enhance penetration 2
• Discard the paring tool after use or dedicate it solely to wart treatment to prevent spreading infection 2

Critical Pitfall to Avoid:

Do not damage surrounding normal skin during paring, as this can spread HPV infection to adjacent areas through autoinoculation 2. This is particularly important given the patient already has four warts, suggesting susceptibility to spread.

Second-Line Treatment (If No Response After 3-4 Months)

Switch to cryotherapy with liquid nitrogen applied every 2 weeks for at least 3 months if salicylic acid fails 1. However, set realistic expectations: plantar warts have inherently lower cure rates (14-39%) with cryotherapy compared to hand warts due to the thick plantar skin 1.

Cryotherapy Protocol:

• Apply liquid nitrogen every 2 weeks for 3-4 months minimum 1
• Always debride/pare the wart before each cryotherapy session to maximize treatment penetration 1
• Consider topical or injected local anesthesia given the patient's significant pain sensitivity 3
• More aggressive double freeze-thaw cycles may improve efficacy to 65% but increase pain, blistering, and scarring risk 1

Alternative Second-Line Option:

Combining salicylic acid with cryotherapy may achieve 86% clearance in some studies, though this increases side effects 1. Given this patient's pain level, combination therapy may be worth the increased discomfort to achieve faster resolution.

Third-Line Options for Resistant Cases

If both salicylic acid and cryotherapy fail after adequate treatment duration:

• 5-Fluorouracil 5% cream under occlusion achieves 95% clearance in plantar warts after 12 weeks of daily application 1
• Contact immunotherapy with diphencyprone (DPC) or SADBE achieves 88% complete clearance over a median of 5 months 1
• Intralesional bleomycin (0.1-1 mg/mL) after local anesthesia, requiring 1-3 treatments 1

Important Prognostic Information

Plantar warts have inherently lower cure rates (14-33%) compared to warts at other body sites due to the thick plantar skin blocking treatment penetration 1. The patient and family need realistic expectations:

• Salicylic acid achieves approximately 33% cure rate for plantar warts 1
• Cryotherapy achieves 30-39% cure rate 1
• Treatment must continue for the full 3-4 months before declaring failure 1, 2
• Patient compliance is often poor due to surrounding skin irritation and prolonged treatment courses 1

Treatment Duration and Follow-Up

Do not stop treatment prematurely - salicylic acid requires a full 3-4 months and cryotherapy needs at least 3 months or six treatments before declaring failure 2. The one-month duration since onset is far too short to consider these warts "non-healing" or treatment-resistant. Most treatments require 3-4 months minimum to show efficacy 1, 2.

Follow-Up Schedule:

• Evaluate the potentially infected wart within 3-5 days
• Once infection is ruled out or resolved, initiate salicylic acid treatment
• Follow up at 4-6 weeks to assess compliance and technique
• Reassess at 3 months before considering treatment failure 1

Treatments to Avoid

Do not use surgical excision - the British Association of Dermatologists assigns this the lowest possible evidence rating (Level 3, Strength D) with no high-quality studies supporting its use 1. Given the patient's significant pain sensitivity, avoid unnecessarily aggressive interventions without trying conservative measures first.