Plantar Wart

Plantar warts (verrucae) are benign epidermal growths on the sole caused by human papillomavirus, mainly types 1, 2 and 4. Weight bearing pushes the lesion inwards, producing a painful, flat or endophytic hyperkeratotic plaque.

• Spread by direct contact and shared wet floors (communal showers, swimming areas, barefoot walking).
• Microtrauma and maceration facilitate infection.
• Higher burden and persistence in children, adolescents, HIV infection, transplant recipients and on immunosuppressants.

Painful on walking and on lateral squeezing, firm hyperkeratotic plaque that interrupts skin lines, with tiny black dots (thrombosed capillaries) on paring.

• Single or clustered (mosaic wart) lesions on pressure sites or heel.
• Differential diagnosis: corn, callus, foreign body, porokeratosis plantaris, acral melanoma, squamous cell carcinoma, verrucous carcinoma, eccrine poroma, tungiasis, keratoderma.
• Complications: pain and gait change, secondary bacterial infection after treatment, scarring from aggressive treatment, spread to other sites, persistent disease in immunosuppression, malignant change (rare).

Clinical, with paring to reveal bleeding black dots and interrupted skin lines.

• Dermoscopy shows red or black dots.
• Biopsy for atypical, ulcerated, pigmented or non responding lesions, and in the immunosuppressed.
• HIV testing in extensive or recalcitrant warts.
• Assess for diabetes and peripheral neuropathy before treatment.

Many resolve spontaneously within 1 to 2 years, so treat when painful, extensive or persistent.

• Supportive: pare dead skin weekly, protective footwear in communal wet areas, cover lesions, do not share towels, padding to offload pressure.
• Pharmacological: salicylic acid 40 percent plaster or 17 to 50 percent paint applied daily after soaking and paring, for up to 12 weeks. Fluorouracil 5 percent cream twice daily under occlusion for resistant lesions. Imiquimod 5 percent cream three times weekly under occlusion. Intralesional bleomycin 1 unit/mL, 0.1 to 1 mL per lesion (maximum 2 units per session) for recalcitrant lesions, with local anaesthesia. Intralesional Candida antigen 0.1 mL every 3 weeks as immunotherapy.
• Procedures: cryotherapy with liquid nitrogen for 10 to 20 seconds per lesion every 2 to 3 weeks (up to 4 to 6 sessions); curettage, laser, electrosurgery or surgical excision for refractory disease (risk of painful scar).
• Special groups: pregnancy, avoid fluorouracil and bleomycin; salicylic acid in small areas and cryotherapy acceptable; diabetes and neuropathy or poor circulation, avoid acid preparations and aggressive destruction and refer to podiatry; HIV, treat more frequently and optimise antiretroviral therapy; children, avoid painful destruction and use salicylic acid.
• Red flags: pigmented, ulcerated or bleeding lesion, rapid growth, no black dots, lesion not on pressure site in adult, non healing after destruction, signs of cellulitis.
• Follow-up: review every 2 to 4 weeks during treatment; stop and reassess at 12 weeks; biopsy if lesion persists beyond 6 months.