Plantar Warts (Verrucae)
Summary
Plantar warts (verrucae) are benign epithelial growths on the sole of the foot caused by Human Papillomavirus (HPV), most commonly types 1, 2, and 4. They are common, especially in children and adolescents, and are transmitted through direct contact or via contaminated surfaces (e.g., swimming pools, communal showers). Plantar warts are typically flat due to pressure from walking and are characterised by interruption of skin lines and black dots (thrombosed capillaries). Most warts resolve spontaneously within 2 years, especially in children. Treatment options include salicylic acid (first-line), cryotherapy, and various destructive methods for persistent lesions.
Key Facts
- Cause: HPV (types 1, 2, 4 most common)
- Transmission: Direct contact, Wet floors (swimming pools)
- Features: Flat, Hyperkeratotic, Black dots (capillaries), Skin line interruption
- Pain: Tender on lateral pressure (pinch), not direct (unlike corns)
- Natural History: Most resolve in 2 years (children)
- Treatment: Salicylic acid (first-line), Cryotherapy
Clinical Pearls
"Black Dots = Wart": Thrombosed capillaries visible as black dots within the lesion, especially after paring.
"Skin Lines Interrupted": Unlike corns, warts interrupt the normal dermatoglyphics (skin lines).
"Pinch Test": Warts are tender on lateral pressure (pinch); Corns are tender on direct pressure.
"Most Go Away": Without treatment, 65% of warts resolve within 2 years in children.
Prevalence
- 10% of population at any time
- Peak: School-age children (10-14 years)
Transmission
- Direct skin-to-skin contact
- Indirect via contaminated surfaces (swimming pools, showers)
- Inoculation through breaks in skin
Risk Factors
| Factor | Notes |
|---|---|
| Age | School-age children |
| Swimming | Wet, macerated skin |
| Shared bathing areas | |
| Immunosuppression | More persistent, extensive |
HPV Infection
- HPV infects basal keratinocytes
- Viral replication in differentiating cells
- Causes epithelial hyperplasia and hyperkeratosis
Why Thrombosed Capillaries?
- Elongated dermal papillae with dilated capillaries
- Trauma → Thrombosis → Black dots
Natural History
- Most warts resolve spontaneously (immune-mediated)
- 65% within 2 years (children)
Appearance
| Feature | Description |
|---|---|
| Location | Sole of foot (plantar surface) |
| Shape | Flat (pressure from walking) |
| Surface | Rough, Hyperkeratotic |
| Black dots | Thrombosed capillaries (visible after paring) |
| Skin lines | Interrupted (not preserved) |
Symptoms
Types
Inspection
- Flat, rough, hyperkeratotic lesion
- Black dots (especially after paring)
- Skin line interruption
Pared Down
- Gentle debridement reveals black dots (diagnostic)
Pinch Test
- Tender on lateral pressure (wart)
- Tender on direct pressure (corn)
Usually Not Required
- Diagnosis is clinical
When to Biopsy
| Indication | Concern |
|---|---|
| Atypical appearance | Amelanotic melanoma, SCC |
| Non-response to treatment | |
| Pigmented lesion | |
| Immunosuppressed patient |
Treatment Approach
┌──────────────────────────────────────────────────────────┐
│ PLANTAR WART MANAGEMENT │
├──────────────────────────────────────────────────────────┤
│ │
│ NO TREATMENT (Option for asymptomatic): │
│ • Most warts resolve spontaneously in 2 years │
│ • Acceptable if not painful │
│ │
│ FIRST-LINE: SALICYLIC ACID │
│ • Available OTC (Bazuka, Compound W) │
│ • Daily application for 12 weeks │
│ • Debride weekly (file down dead skin) │
│ • Protect surrounding skin (Vaseline) │
│ • Efficacy: 70-80% cure │
│ │
│ SECOND-LINE: CRYOTHERAPY │
│ • Liquid nitrogen (-196°C) │
│ • Performed by GP/Dermatologist │
│ • Freeze-thaw cycles │
│ • Painful; May cause blistering │
│ • Repeat every 2-3 weeks │
│ • Efficacy: 50-70% │
│ │
│ THIRD-LINE (RESISTANT WARTS): │
│ • Duct tape occlusion │
│ • Intralesional bleomycin │
│ • Immunotherapy (Contact sensitisation) │
│ • Surgical curettage (rarely; risk of scarring) │
│ • Laser ablation │
│ │
│ PREVENTION: │
│ • Avoid walking barefoot in communal areas │
│ • Cover wart when swimming │
│ • Don't share towels/shoes │
│ │
└──────────────────────────────────────────────────────────┘
Of Warts
- Pain on walking
- Spread (mosaic warts)
- Rarely: Underlying malignancy misdiagnosed
Of Treatment
- Scarring (especially surgical)
- Hypopigmentation (cryotherapy)
- Pain, Blistering (cryotherapy)
Natural History
- 65% resolve within 2 years (children)
- Less spontaneous resolution in adults
With Treatment
- Salicylic acid: 70-80% cure
- Cryotherapy: 50-70% cure
- Recurrence possible
Key Guidelines
- BAD: Guidelines on Cutaneous Warts
Key Evidence
Salicylic Acid vs Cryotherapy
- Similar efficacy; Salicylic acid less painful and cheaper
What Are Plantar Warts?
Plantar warts (also called verrucae) are warts on the soles of your feet caused by a virus (HPV). They are common and usually harmless.
How Do You Get Them?
The virus spreads through skin-to-skin contact or from walking barefoot on contaminated floors (like swimming pools or gym showers).
What Do They Look Like?
- Flat, rough patches of skin on the sole
- Small black dots (tiny blood vessels)
- Skin lines (fingerprint-like ridges) are interrupted
Do They Need Treatment?
Most warts go away on their own within 2 years, especially in children. Treatment is only needed if they're painful or bothersome.
How Are They Treated?
- Salicylic acid: Applied daily at home; works for most warts
- Cryotherapy: Freezing with liquid nitrogen — done by a doctor
How Can I Prevent Spreading Them?
- Wear flip-flops in communal areas
- Cover the wart when swimming
- Don't share towels or shoes
Primary Guidelines
- British Association of Dermatologists. Guidelines on the Management of Cutaneous Warts.
Key Studies
- Kwok CS, et al. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012. PMID: 22972127