Plantar Warts (Verrucae)

1. Clinical Overview

Summary

Plantar warts (verrucae plantares) are benign epithelial proliferations on the plantar surface of the feet caused by infection with Human Papillomavirus (HPV), primarily types 1, 2, 4, 27, and 57. [1,2] They represent one of the most common dermatological presentations in primary care and podiatry, affecting approximately 7-12% of the population at any given time, with peak incidence in school-aged children and adolescents. [1,3]

The pathognomonic features of plantar warts include interruption of dermatoglyphic (skin) lines, pinpoint black dots representing thrombosed capillaries within elongated dermal papillae, and tenderness on lateral compression (pinch test) rather than direct pressure. [2,4] These features distinguish plantar warts from other hyperkeratotic plantar lesions, particularly corns (clavi) and calluses, which preserve dermatoglyphics and exhibit pain on direct pressure.

A critical aspect of plantar wart management is understanding the high rate of spontaneous resolution—approximately 65-78% of warts in children resolve within 2 years without treatment. [5,6] This natural history informs the conservative "watchful waiting" approach often recommended for asymptomatic lesions, particularly in immunocompetent children.

Treatment, when indicated, follows a stepwise approach prioritizing salicylic acid (17-40% concentration) as first-line therapy due to superior cost-effectiveness and patient acceptability. [7,8] Cryotherapy with liquid nitrogen remains a popular second-line option, though meta-analyses demonstrate comparable or slightly inferior efficacy compared to salicylic acid. [9,10] Recalcitrant warts may require advanced therapies including intralesional immunotherapy (Candida antigen, MMR), bleomycin injection, or contact sensitization (diphencyprone, DPCP). [11,12]

Key Facts

Clinical Pearls

"Black Dots = Thrombosed Capillaries": The pathognomonic black dots within plantar warts represent thrombosed capillaries in elongated dermal papillae, best visualized after gentle paring of the hyperkeratotic surface. [2,4]

"Dermatoglyphics Interrupted": Unlike corns and calluses (which preserve skin lines), plantar warts disrupt the normal fingerprint-like dermatoglyphic patterns—a key diagnostic feature. [4]

"Pinch Test for Warts": Warts are characteristically tender with lateral compression (squeezing from the sides), whereas corns are tender with direct vertical pressure. [4]

"HPV-1 vs HPV-2": HPV-1 causes deep, solitary, painful "myrmecia" warts; HPV-2 causes superficial mosaic warts (clusters). HPV-1 lesions are more resistant to treatment. [13,14]

"Two-Thirds Resolve Spontaneously": In immunocompetent children, 65-78% of plantar warts resolve within 2 years without any treatment—counseling on natural history is essential. [5,6]

"Watchful Waiting is Valid": For asymptomatic warts, particularly in children, observation without treatment is an evidence-based first-line approach. [15]

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2. Epidemiology

Prevalence and Incidence

Plantar warts are among the most common viral infections of the skin, with reported prevalence rates varying by age group and population studied:

The incidence is highest in adolescence (10-19 years), with a gradual decline thereafter, likely reflecting both reduced exposure and acquired type-specific immunity to HPV. [3]

Transmission and Risk Factors

Plantar warts are transmitted through direct skin-to-skin contact or indirect contact with contaminated surfaces. The virus requires a portal of entry through disrupted epithelium (microtrauma, maceration). [1,2]

High-Risk Environments:

• Swimming pools and communal showers
• Gymnasiums and sports facilities
• Communal changing rooms
• Barefoot walking areas

Individual Risk Factors:

Exam Detail: HPV Genotype Epidemiology:

Different HPV types demonstrate distinct clinical and epidemiological patterns:

• HPV-1 (60-65% of plantar warts): Deep, endophytic "myrmecia" warts; solitary; more painful; more resistant to treatment; longer duration. [13,14]
• HPV-2 (10-20%): Superficial mosaic warts; clusters of small warts; less painful; more responsive to treatment.
• HPV-4 (5-10%): Similar to HPV-2; associated with mosaic patterns.
• HPV-27, HPV-57 (5-10%): Flat warts, occasionally plantar.

HPV genotype influences both natural history and treatment response. HPV-1 warts have lower spontaneous clearance rates (40% at 2 years vs 80% for HPV-2) and reduced response to cryotherapy. [13,14]

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3. Aetiology and Pathophysiology

Viral Characteristics

Human papillomaviruses are small, non-enveloped, double-stranded DNA viruses of the Papillomaviridae family. Over 200 HPV types have been identified, with cutaneous warts primarily caused by alpha-HPV (HPV-2, -27, -57) and mu-HPV (HPV-1, -63) genera. [2]

HPV-1 Characteristics:

• Genus: Mu-papillomavirus
• Genome: ~8,000 base pairs, circular dsDNA
• Tropism: Basal keratinocytes of plantar epidermis
• Replication: Exclusively in differentiating keratinocytes (requires cellular differentiation machinery)
• Oncogenic potential: None (benign infection)

Pathogenesis

The development of plantar warts follows a characteristic sequence:

1. Viral Entry (Inoculation Phase)

• HPV enters through microtrauma in plantar skin (abraded stratum corneum)
• Moisture and maceration (e.g., swimming pools) facilitate entry [1]
• Virus infects basal keratinocytes (stem cell compartment)

2. Viral Replication (Productive Infection)

• HPV genome maintained as episome (not integrated into host DNA)
• Viral E6 and E7 proteins promote cell proliferation by inactivating p53 and Rb tumor suppressors
• Productive viral replication occurs in suprabasal differentiating keratinocytes
• Viral assembly in upper epidermis with shedding of infectious virions

3. Clinical Lesion Formation

4. Endophytic Growth Pattern

• Unlike common warts (exophytic), plantar warts grow inward (endophytic) due to:
  • Pressure from ambulation compresses the lesion into dermis
  • Thick plantar stratum corneum resists outward growth
  • Results in deeper, more painful lesions (especially HPV-1 "myrmecia")

Immunology and Spontaneous Resolution

The high rate of spontaneous resolution reflects cell-mediated immune clearance:

Immune Mechanisms:

• Th1 response (IFN-γ, IL-2): Critical for wart clearance [17]
• Cytotoxic T cells (CD8+): Destroy HPV-infected keratinocytes
• Natural killer cells: Early innate response
• Langerhans cells: Antigen presentation (often reduced in warts—viral immune evasion)

HPV Immune Evasion:

• Intracellular lifecycle (no viremia, minimal immune exposure)
• Low viral protein expression (avoids immune detection)
• Downregulation of MHC class I (evades CD8+ T cells)
• Minimal inflammation (lack of danger signals)

Exam Detail: Why Do Some Warts Persist?

Chronic plantar warts reflect failure of cell-mediated immunity:

1. Local immune tolerance: HPV establishes "immune privilege" with minimal inflammation
2. HPV-1 deeper location: Harder for immune cells to access dermal-epidermal junction
3. Individual genetic factors: HLA types (e.g., HLA-DRB101, DRB104) associated with persistent warts
4. Immunosuppression: Profound effect in transplant recipients (50-90% prevalence) [16]

Spontaneous clearance rates:

• Children: 65-78% at 2 years [5,6]
• Adults: 30-40% at 2 years (lower than children)
• Immunosuppressed: less than 10% at 2 years

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4. Clinical Presentation

Morphology and Appearance

Plantar warts exhibit distinct morphological features that differentiate them from other hyperkeratotic plantar lesions:

Clinical Variants

1. Solitary Plantar Wart (Verruca Simplex)

• Most common presentation (70-80% of cases)
• Single, well-demarcated lesion
• Diameter: 5-15 mm (can enlarge to 20-30 mm)
• Depth: Often endophytic, extending into dermis (HPV-1)
• Symptoms: Pain on ambulation if over weight-bearing area

2. Myrmecia ("Ant Hill" Wart—HPV-1)

• Deep, endophytic plantar wart
• Highly keratotic with central depression
• Markedly painful due to deep dermal pressure on nerve endings
• Black dots often numerous and prominent
• Most resistant to treatment [13,14]
• Name derives from Greek "myrmex" (ant) due to appearance

3. Mosaic Wart (HPV-2, HPV-4)

• Cluster of multiple small warts (2-5 mm each) confluent into plaques
• Superficial (less endophytic than myrmecia)
• Less painful than solitary warts
• Often located on non-weight-bearing areas (arch, heel)
• More responsive to treatment than HPV-1 lesions [13,14]

4. Periungual Plantar Wart

• Rare variant around toenail (periungual/subungual)
• Can cause nail dystrophy, pain, secondary infection
• Difficult to treat due to location

Symptoms

Pain Characteristics:

• Lateral compression pain (pathognomonic "pinch test"): Squeezing wart from sides causes sharp pain [4]
• Direct pressure pain: Variable—depends on location (weight-bearing vs non-weight-bearing)
• Deep myrmecia warts: Severe pain on walking ("feels like stepping on a pebble")
• Mosaic warts: Usually less painful

Functional Impact:

• Altered gait/biomechanics to avoid painful areas
• Difficulty with footwear (especially tight shoes)
• Impaired sports participation
• Psychological impact (cosmetic concern, embarrassment in communal settings)

Natural History

The natural course of plantar warts is characterized by high spontaneous clearance rates, particularly in children:

Spontaneous Resolution Rates:

• 6 months: ~15-20% [5,6]
• 1 year: ~30-40%
• 2 years: 65-78% (children) [5,6]; 30-40% (adults)
• 3 years: ~80-85% (children)

Factors Predicting Spontaneous Clearance:

• Younger age (children > adults)
• HPV-2/HPV-4 (superficial mosaic warts) > HPV-1 (myrmecia) [13,14]
• Shorter duration (less than 6 months better prognosis)
• Smaller size (less than 10 mm)
• Immunocompetence (vs immunosuppression)

Factors Predicting Persistence:

• HPV-1 genotype (40% clearance at 2 years vs 80% for HPV-2) [13,14]
• Longer duration (>12 months)
• Larger size (>15 mm)
• Immunosuppression (transplant, HIV, biologics) [16]
• Multiple warts (mosaic pattern may paradoxically persist longer than expected)

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5. Clinical Examination

Inspection

Systematic visual examination of the plantar foot should assess:

1. Location

• Weight-bearing areas (metatarsal heads, heel) vs non-weight-bearing (arch)
• Unilateral vs bilateral (bilateral suggests contamination, not immune deficiency)
• Proximity to pressure points

2. Morphology

• Size: Measure diameter with ruler (baseline for monitoring)
• Shape: Round, oval, irregular
• Number: Solitary vs mosaic (multiple)
• Surface: Hyperkeratotic, rough, presence of black dots

3. Dermatoglyphics (Skin Lines)

• KEY DIAGNOSTIC FEATURE: Observe skin lines (fingerprint-like ridges)
  • "Plantar wart: Lines are INTERRUPTED (do not cross the lesion)"
  • "Corn/callus: Lines are PRESERVED (continue across the lesion)"

4. Color

• Typically skin-colored to yellowish (hyperkeratosis)
• Black/dark brown dots: Thrombosed capillaries (pathognomonic)
• Unusual pigmentation: Consider amelanotic melanoma (red flag—biopsy if atypical)

Palpation

Pinch Test (Lateral Compression Test):

• Technique: Gently compress the lesion from the sides (lateral pressure) using thumb and index finger
• Positive test: Sharp pain with lateral compression (pathognomonic for wart) [4]
• Negative test: Minimal pain with lateral compression

Direct Pressure Test:

• Technique: Press directly on the lesion with finger or blunt probe
• Wart: Variable pain (depends on depth and location)
• Corn: Sharp pain with direct pressure (distinguishes from wart)

Paring (Debridement) Test:

• Technique: Gently pare (shave) the hyperkeratotic surface with scalpel blade (if clinically uncertain)
• Wart: Reveals black dots (thrombosed capillaries) and pinpoint bleeding [2,4]
• Corn: Reveals translucent central core (no black dots)
• Callus: Uniform reduction in thickness (no core, no black dots)

Examination Checklist

┌─────────────────────────────────────────────────────────────┐
│   PLANTAR WART CLINICAL EXAMINATION PROTOCOL                 │
├─────────────────────────────────────────────────────────────┤
│                                                              │
│  HISTORY:                                                    │
│  ☐ Duration of lesion (months/years)                        │
│  ☐ Pain on walking (severity 0-10)                          │
│  ☐ Previous treatments attempted                            │
│  ☐ Recent swimming pool/communal shower exposure            │
│  ☐ Immunosuppression (HIV, transplant, biologics)           │
│  ☐ Impact on daily activities (gait, sports, footwear)      │
│                                                              │
│  INSPECTION:                                                 │
│  ☐ Location (weight-bearing vs non-weight-bearing)          │
│  ☐ Size (measure diameter in mm)                            │
│  ☐ Number (solitary vs mosaic cluster)                      │
│  ☐ Dermatoglyphics (INTERRUPTED vs preserved)               │
│  ☐ Black dots visible (thrombosed capillaries)              │
│  ☐ Surface (hyperkeratotic, rough)                          │
│  ☐ Unusual features (ulceration, bleeding, pigmentation)    │
│                                                              │
│  PALPATION:                                                  │
│  ☐ Pinch test (lateral compression—POSITIVE if painful)     │
│  ☐ Direct pressure (variable pain)                          │
│  ☐ Paring test (if uncertain—reveals black dots)            │
│                                                              │
│  RED FLAGS (biopsy indicated):                               │
│  ☐ Atypical pigmentation (consider amelanotic melanoma)     │
│  ☐ Rapid growth or ulceration                               │
│  ☐ Bleeding without trauma                                  │
│  ☐ Non-response to standard treatment (>6 months)           │
│  ☐ Immunosuppressed patient with atypical lesion            │
│                                                              │
│  DIFFERENTIAL DIAGNOSIS TO EXCLUDE:                          │
│  ☐ Corn (clavus): Direct pressure pain, preserved skin lines│
│  ☐ Callus: Diffuse, preserved skin lines, no black dots     │
│  ☐ Amelanotic melanoma: Atypical, non-responsive            │
│  ☐ Porokeratosis: Raised border, central depression         │
│  ☐ Foreign body granuloma: History of penetrating injury    │
│                                                              │
└─────────────────────────────────────────────────────────────┘

Exam Detail: OSCE/Clinical Skills Station Tips:

When examining a patient with suspected plantar warts in an OSCE:

1. Introduce and position: "I'm going to examine your foot. Please sit comfortably and place your foot on this stool."

2. Inspect systematically: "I can see a well-demarcated hyperkeratotic lesion on the plantar surface of your right foot, approximately 10 mm in diameter, located over the first metatarsal head."

3. Verbalize key findings: "I note that the skin lines—the dermatoglyphics—are interrupted by this lesion, which is a key feature distinguishing a wart from a corn or callus."

4. Demonstrate pinch test: "I'm now going to test for tenderness. With lateral compression—the pinch test—there is sharp pain, which is characteristic of a plantar wart rather than a corn."

5. Offer paring: "If I were uncertain, I would gently pare the surface to look for black dots—thrombosed capillaries—which are pathognomonic for a wart."

6. Complete examination: "I would also examine the rest of both feet to look for additional lesions and assess for any underlying predisposing factors."

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6. Investigations

Clinical Diagnosis (Standard Approach)

Plantar warts are a clinical diagnosis based on characteristic morphology and do not routinely require investigations. [1,2]

Diagnostic Features (No Investigation Needed):

• Interruption of dermatoglyphics
• Pinpoint black dots (thrombosed capillaries)
• Lateral compression tenderness (pinch test)
• Hyperkeratotic surface

When to Investigate

Investigations are reserved for atypical presentations or diagnostic uncertainty:

Histopathology (When Biopsy Performed)

Characteristic Histological Features of Plantar Warts:

Immunohistochemistry:

• Not routinely required for diagnosis
• p16 staining: Positive (indicates HPV infection)
• Ki-67: Increased proliferation in basal/suprabasal layers

Dermoscopy

Non-invasive aid to clinical diagnosis (increasingly available in primary care and dermatology):

Dermoscopic Features of Plantar Warts:

• Red/brown/black dots: Thrombosed capillaries in dermal papillae (pathognomonic)
• Hemorrhagic streaks: Linear thrombosed capillaries
• Absence of skin line preservation: Dermatoglyphics interrupted
• Peripheral hyperkeratotic rim: Well-demarcated border

Dermoscopy to Differentiate from Melanoma:

• Melanoma: Pigment network, blue-white veil, atypical vessels, irregular pigmentation
• Wart: Regular red/black dots, no pigment network

HPV Genotyping (Research Tool, Not Routine)

Methods:

• PCR (polymerase chain reaction) of lesional tissue
• Identifies specific HPV type (HPV-1, -2, -4, etc.)

Clinical Utility:

• NOT routinely performed in standard practice
• May guide prognosis: HPV-1 (more resistant) vs HPV-2 (more responsive) [13,14]
• Epidemiological research and vaccine development

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7. Management

Treatment Principles

The management of plantar warts is guided by several key principles:

1. Natural history: 65-78% of warts in children resolve spontaneously within 2 years [5,6]
2. No universally effective treatment: All modalities have variable efficacy (50-80% clearance)
3. Patient-centered approach: Balance efficacy, pain, cost, and patient preference
4. Stepwise escalation: Start with least invasive, escalate if refractory
5. Shared decision-making: Watchful waiting vs active treatment (both acceptable) [15]

Treatment Algorithm

┌──────────────────────────────────────────────────────────────────┐
│   PLANTAR WART MANAGEMENT ALGORITHM                              │
├──────────────────────────────────────────────────────────────────┤
│                                                                  │
│  STEP 0: ASSESS TREATMENT NEED                                   │
│  ├─ Asymptomatic + Child → Consider WATCHFUL WAITING (2 years)  │
│  ├─ Symptomatic (painful, cosmetic, functional) → Treat          │
│  └─ Immunosuppressed → Treat (low spontaneous clearance)         │
│                                                                  │
│  STEP 1: FIRST-LINE (Home Treatment, 12 Weeks)                   │
│  ┌────────────────────────────────────────────────────┐          │
│  │  SALICYLIC ACID 17-40% (Daily Application)        │          │
│  │  • Apply to wart after soaking foot (10-15 min)   │          │
│  │  • Protect surrounding skin (petroleum jelly)     │          │
│  │  • Occlude overnight (duct tape optional)         │          │
│  │  • Debride (pumice/emery board) weekly            │          │
│  │  • Continue for 12 weeks                          │          │
│  │  • Efficacy: 70-75% clearance [7,8]               │          │
│  └────────────────────────────────────────────────────┘          │
│           ↓ (If no response at 12 weeks)                         │
│                                                                  │
│  STEP 2: SECOND-LINE (Clinic-Based)                              │
│  ┌────────────────────────────────────────────────────┐          │
│  │  CRYOTHERAPY (Liquid Nitrogen -196°C)             │          │
│  │  • Freeze-thaw cycles (10-30 seconds per cycle)   │          │
│  │  • Repeat every 2-3 weeks (max 4-6 sessions)      │          │
│  │  • Debride before each session                    │          │
│  │  • Efficacy: 50-70% clearance [9,10]              │          │
│  │  • Painful; may blister; risk of hypopigmentation │          │
│  └────────────────────────────────────────────────────┘          │
│  OR                                                              │
│  ┌────────────────────────────────────────────────────┐          │
│  │  COMBINATION: Salicylic Acid + Cryotherapy        │          │
│  │  • May improve efficacy vs monotherapy            │          │
│  └────────────────────────────────────────────────────┘          │
│           ↓ (If refractory after 6 months)                       │
│                                                                  │
│  STEP 3: THIRD-LINE (Recalcitrant Warts, Specialist)             │
│  ┌────────────────────────────────────────────────────┐          │
│  │  INTRALESIONAL IMMUNOTHERAPY                      │          │
│  │  • Candida antigen 0.1-0.3 mL intralesional [11]  │          │
│  │  • OR MMR vaccine intralesional                   │          │
│  │  • Repeat every 3-4 weeks (max 3-5 sessions)      │          │
│  │  • Efficacy: 60-80% clearance [11,12]             │          │
│  │  • Distant wart clearance (immunological memory)  │          │
│  └────────────────────────────────────────────────────┘          │
│  OR                                                              │
│  ┌────────────────────────────────────────────────────┐          │
│  │  BLEOMYCIN INTRALESIONAL                          │          │
│  │  • 0.1% bleomycin injection into wart [18]        │          │
│  │  • Single session (may repeat if needed)          │          │
│  │  • Painful; risk of necrosis, scarring            │          │
│  │  • Efficacy: 60-95% (variable studies) [18]       │          │
│  └────────────────────────────────────────────────────┘          │
│  OR                                                              │
│  ┌────────────────────────────────────────────────────┐          │
│  │  CONTACT SENSITIZATION (Immunotherapy)            │          │
│  │  • Diphencyprone (DPCP) topical application [12]  │          │
│  │  • Sensitization phase → challenge phase          │          │
│  │  • Weekly applications for 3-6 months             │          │
│  │  • Efficacy: 60-80% clearance [12]                │          │
│  └────────────────────────────────────────────────────┘          │
│                                                                  │
│  STEP 4: FOURTH-LINE (Last Resort, Rarely Needed)                │
│  ┌────────────────────────────────────────────────────┐          │
│  │  SURGICAL EXCISION / CURETTAGE                    │          │
│  │  • High recurrence rate (30-50%)                  │          │
│  │  • Risk of painful scar (plantar surface)         │          │
│  │  • AVOID unless all else fails                    │          │
│  └────────────────────────────────────────────────────┘          │
│  OR                                                              │
│  ┌────────────────────────────────────────────────────┐          │
│  │  LASER ABLATION (CO2, Pulsed-Dye Laser)           │          │
│  │  • Specialist-only                                │          │
│  │  • Expensive; variable efficacy; scarring risk    │          │
│  └────────────────────────────────────────────────────┘          │
│                                                                  │
└──────────────────────────────────────────────────────────────────┘

Watchful Waiting (Active Surveillance)

Indications:

• Asymptomatic warts (no pain, no functional impairment)
• Children and adolescents (high spontaneous clearance: 65-78% at 2 years) [5,6]
• Patient preference for non-intervention
• Small, recent-onset warts (less than 6 months duration)

Patient Counseling:

• Natural history: Most warts resolve without treatment (2/3 within 2 years)
• Monitor for symptoms: Pain, enlargement, spread
• Hygiene measures: Cover wart when swimming, avoid barefoot walking in communal areas
• Re-evaluate at 6-12 months

Evidence:

• Cochrane review: No treatment has significantly better efficacy than placebo in achieving complete wart clearance [7]
• British Association of Dermatologists: Watchful waiting is a valid first-line approach [15]

First-Line: Salicylic Acid

Mechanism:

• Keratolytic agent: Softens and removes hyperkeratotic tissue
• Cytotoxic effect: Destroys wart-infected keratinocytes
• Immune stimulation: Minor inflammatory response may enhance immune clearance

Formulations:

• 17% salicylic acid (OTC—Compound W, Bazuka, Occlusal)
• 40% salicylic acid (prescription—higher concentration for resistant warts)
• 5-FU/salicylic acid combination (off-label—may improve efficacy) [19]

Application Protocol:

1. Soak foot in warm water for 10-15 minutes (softens keratin)
2. Debride wart surface gently with pumice stone or emery board
3. Protect surrounding skin with petroleum jelly (prevents irritation)
4. Apply salicylic acid to wart surface only (avoid normal skin)
5. Occlude with duct tape or adhesive bandage overnight (optional—may enhance penetration) [20]
6. Repeat daily for 12 weeks (minimum duration for efficacy assessment)
7. Debride weekly to remove dead tissue

Efficacy:

• Meta-analysis: 73% (95% CI 63-81%) complete clearance at 12 weeks [7,8]
• Superior to placebo (RR 2.8, 95% CI 1.5-5.2) [7]
• Similar efficacy to cryotherapy but better tolerated [8,10]

Adverse Effects:

• Local irritation (erythema, maceration)—common, usually mild
• Chemical burn if applied to normal skin (protect with petroleum jelly)
• Rare: Systemic salicylate toxicity (only with extensive application)

Contraindications:

• Salicylate allergy
• Diabetes with neuropathy (risk of unnoticed tissue damage)
• Peripheral vascular disease (impaired wound healing)
• Children less than 2 years (theoretical systemic absorption risk—use with caution)

Second-Line: Cryotherapy

Mechanism:

• Tissue destruction: Intracellular ice crystal formation → cell lysis
• Vascular damage: Thrombosis of dermal capillaries
• Immunostimulation: Release of HPV antigens → enhanced immune response

Technique:

• Liquid nitrogen application (-196°C) via:
  • Cotton swab (most common in UK primary care)
  • Cryospray gun (more controlled, deeper freeze)
• Freeze-thaw cycles: 10-30 seconds per cycle (until 1-2 mm ice halo visible around wart)
• Debridement: Remove hyperkeratotic tissue before freezing (enhances penetration)
• Repeat sessions: Every 2-3 weeks (maximum 4-6 sessions recommended)

Efficacy:

• Meta-analysis: 49% (95% CI 30-69%) complete clearance [9,10]
• NOT superior to salicylic acid (similar or slightly lower efficacy) [10]
• Single aggressive freeze may be more effective than multiple gentle freezes [9]

Adverse Effects:

• Pain: During and after treatment (significant—main patient complaint)
• Blistering: Common (within 24 hours post-treatment)
• Hypopigmentation: Permanent in 10-20% (especially darker skin types)
• Scarring: Rare, but risk increases with aggressive/repeated treatment
• Rarely: Nerve damage (plantar digital nerves), infection

Contraindications:

• Peripheral vascular disease (risk of ulceration/gangrene)
• Raynaud's phenomenon / cold urticaria
• Cryoglobulinemia
• Very young children (pain tolerance)

Evidence:

• Cochrane review: Cryotherapy vs salicylic acid—no significant difference in efficacy [7,10]
• Aggressive cryotherapy (longer freeze, single session) vs multiple gentle sessions: Conflicting evidence [9]

Third-Line: Intralesional Immunotherapy

Rationale: Stimulate cell-mediated immune response against HPV by injecting immunogenic antigens directly into the wart, inducing Th1 inflammatory cascade and cytotoxic T-cell activation. [11,12]

Candida Antigen Immunotherapy:

• Mechanism: Delayed-type hypersensitivity reaction to Candida (most patients pre-sensitized) → cross-reactive immune response against HPV-infected cells
• Dose: 0.1-0.3 mL Candida antigen (e.g., Candin 1:1000) intralesional injection
• Frequency: Every 3-4 weeks (maximum 3-5 sessions)
• Technique: Inject into base of wart until blanching observed (indicates adequate distribution)

Efficacy:

• RCT: 74% complete clearance vs 20% placebo (pless than 0.001) [11]
• Distant wart clearance: 30-50% of untreated warts also clear (immunological memory) [11]
• Superior to intralesional PPD (purified protein derivative) [11]

Adverse Effects:

• Local pain (during injection and 24-48 hours post)
• Erythema, swelling, pruritus at injection site
• Flu-like symptoms (rare—systemic immune activation)

MMR Vaccine Intralesional Immunotherapy:

• Alternative to Candida antigen (if Candida not available)
• 0.1-0.3 mL MMR vaccine injected intralesionally
• Similar mechanism and efficacy to Candida antigen [12]

Contact Sensitization (Diphencyprone—DPCP):

• Mechanism: Induce allergic contact dermatitis to DPCP → immune activation against wart
• Protocol:
  1. Sensitization phase: Apply high-concentration DPCP (2%) to forearm (induces sensitization over 2 weeks)
  2. Challenge phase: Apply low-concentration DPCP (0.01-0.1%) to wart weekly, titrate to mild eczematous reaction
  3. Duration: 3-6 months (weekly applications)
• Efficacy: 60-80% clearance in recalcitrant warts [12]
• Specialist use only (dermatology)

Fourth-Line: Bleomycin, Surgery, Laser

Bleomycin Intralesional Injection:

• Mechanism: Cytotoxic antibiotic (inhibits DNA synthesis) → direct destruction of wart tissue
• Dose: 0.1% bleomycin sulfate, 0.1-0.2 mL per wart (max 2 mg total dose per session)
• Technique: Multiple puncture technique (inject into wart base) OR microneedling application [18]
• Efficacy: 60-95% clearance (variable across studies—quality of evidence moderate) [18]
• Adverse effects:
  • "Pain: Severe pain during/after injection (main limitation)"
  • "Raynaud's phenomenon: Reported (avoid in patients with vascular disease)"
  • "Eschar formation: Black necrotic crust (heals over 2-4 weeks)"
  • "Scarring: Permanent scar possible (plantar surface risk)"
  • "Flagellate hyperpigmentation: Rare systemic effect"

Surgical Excision / Curettage:

• Indications: Last resort only (failed all other treatments)
• Technique: Scalpel excision, electrodessication and curettage (ED&C), shave excision
• Recurrence rate: 30-50% (high—viral reservoir remains in surrounding tissue) [1]
• Complications:
  • Painful scar (plantar surface—can be more disabling than original wart)
  • Keloid formation (especially in predisposed individuals)
  • Recurrence within scar (difficult to re-treat)
• Recommendation: AVOID unless absolutely necessary [1,15]

Laser Therapy:

• Pulsed-dye laser (PDL): Targets hemoglobin in wart capillaries → selective photothermolysis → vascular destruction
  • "Efficacy: 50-70% clearance (variable studies)"
  • Less scarring than surgery
  • Expensive, specialist-only
• CO2 laser: Ablative—vaporizes wart tissue
  • High recurrence rate (similar to surgery)
  • Risk of scarring
  • Not recommended as routine treatment [15]

Special Populations

Immunosuppressed Patients (Transplant, HIV, Biologics):

• Prevalence: 50-90% of transplant recipients develop warts [16]
• Characteristics: Multiple, extensive, recalcitrant, higher risk of malignant transformation (SCC)
• Management:
  • Aggressive treatment (low spontaneous clearance)
  • Consider immunotherapy (Candida, DPCP) [11,12]
  • Monitor for malignant change (biopsy atypical lesions)
  • Optimize immunosuppression (reduce if medically feasible)
  • "Retinoids (oral acitretin): May reduce wart burden in severe cases (off-label)"

Children:

• First-line: Watchful waiting (high spontaneous clearance) [5,6]
• If treatment needed: Salicylic acid (painless, home-based)
• Avoid: Painful treatments (cryotherapy, bleomycin) unless absolutely necessary
• Counseling: Reassure parents—most warts resolve without treatment

Pregnancy:

• Salicylic acid: Avoid extensive application (theoretical systemic absorption—salicylate toxicity)
• Cryotherapy: Safe (local treatment, no systemic effects)
• Bleomycin: Contraindicated (teratogenic)
• Recommendation: Defer treatment to postpartum if possible (warts often regress after delivery)

Prevention

Personal Hygiene Measures:

• Wear footwear (flip-flops) in communal showers, swimming pools, gyms
• Avoid direct contact with warts (own or others)
• Do not share towels, socks, shoes
• Cover warts with waterproof plaster when swimming (reduce viral shedding)
• Keep feet dry (moisture facilitates viral transmission)

Treatment of Existing Warts:

• Prompt treatment reduces autoinoculation (spread to other areas)
• Avoid picking or scratching warts (spreads virus)

No Effective Vaccine:

• HPV vaccines (Gardasil, Cervarix) target oncogenic genital HPV types (16, 18, etc.)
• Do NOT protect against cutaneous HPV types (HPV-1, -2, -4)
• No licensed vaccine for plantar warts currently available

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8. Complications

Complications of Warts (Untreated)

Complications of Treatment

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9. Prognosis and Outcomes

Natural History (Untreated)

The prognosis of plantar warts is highly favorable, particularly in immunocompetent children:

Spontaneous Clearance Rates:

Factors Influencing Prognosis:

Favorable (High Clearance):

• Young age (children > adults)
• Short duration (less than 6 months)
• Small size (less than 10 mm)
• HPV-2/HPV-4 genotype (superficial mosaic warts) [13,14]
• Immunocompetence
• Single wart (vs multiple/mosaic)

Unfavorable (Low Clearance):

• HPV-1 genotype (40% clearance at 2 years) [13,14]
• Long duration (>12 months)
• Large size (>15 mm)
• Deep endophytic warts (myrmecia)
• Immunosuppression (transplant, HIV, biologics) [16]
• Multiple warts

With Treatment

Treatment Success Rates (Complete Clearance):

Key Evidence:

• Cochrane systematic review (Kwok et al., 2012): Salicylic acid vs placebo—RR 2.8 (95% CI 1.5-5.2) for complete clearance. [7]
• Meta-analysis cryotherapy (García-Oreja et al., 2022): 49% (95% CI 30-69%) clearance—NOT superior to salicylic acid. [10]
• Candida antigen RCT (Nofal et al., 2022): 74% clearance vs 20% placebo (pless than 0.001). [11]

Recurrence

Recurrence Rates:

• All treatments: 10-50% recurrence within 1 year (varies by modality)
• Highest recurrence: Surgery (30-50%)—virus remains in surrounding tissue [1]
• Lowest recurrence: Immunotherapy (10-20%)—systemic immune memory [11,12]

Factors Predicting Recurrence:

• Incomplete initial clearance (residual wart tissue)
• Immunosuppression
• Re-exposure (swimming pools, communal showers)
• HPV-1 genotype (more persistent)

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10. Evidence and Guidelines

Key Guidelines

1. British Association of Dermatologists (BAD): Guidelines on the Management of Cutaneous Warts (2014)

• First-line: Salicylic acid (17-40%) for 12 weeks
• Second-line: Cryotherapy (liquid nitrogen) every 2-3 weeks
• Watchful waiting: Valid first-line option, especially in children
• Avoid: Surgical excision (high recurrence, scarring risk)
• Grade of recommendation: B (based on moderate-quality evidence)

2. American Academy of Dermatology (AAD): Guidelines for Wart Treatment

• Salicylic acid and cryotherapy recommended as first-/second-line
• Combination therapy may improve efficacy
• Patient preference should guide treatment selection

3. NHS Clinical Knowledge Summaries (CKS): Warts and Verrucae

• Self-limiting condition (no treatment required in many cases)
• OTC salicylic acid for symptomatic warts
• Refer to podiatry/dermatology if refractory

Key Evidence

Systematic Reviews and Meta-Analyses:

1. Cochrane Review: Topical Treatments for Cutaneous Warts (Kwok et al., 2012) [7]

• Salicylic acid vs placebo: RR 2.8 (95% CI 1.5-5.2)—significant benefit
• Cryotherapy vs placebo: RR 2.0 (95% CI 0.7-6.0)—not statistically significant
• Salicylic acid vs cryotherapy: No significant difference
• Conclusion: Salicylic acid superior to placebo; cryotherapy evidence weaker

2. Meta-Analysis: Efficacy of Cryotherapy for Plantar Warts (García-Oreja et al., 2022) [10]

• Pooled complete clearance rate: 49% (95% CI 30-69%)
• NOT superior to salicylic acid
• Single aggressive freeze may be more effective than multiple gentle sessions
• High heterogeneity between studies

3. Systematic Review: Topical Treatment for Plantar Warts (García-Oreja et al., 2021) [8]

• Salicylic acid: 73% clearance (95% CI 63-81%)
• 5-FU/salicylic acid combination: 75% clearance (superior to monotherapy)
• Bleomycin: 60-95% clearance (wide variability)
• Imiquimod: 50-60% clearance (moderate evidence)

Randomized Controlled Trials:

4. Intralesional Candida Antigen vs Placebo (Nofal et al., 2022) [11]

• 74% complete clearance (Candida) vs 20% (placebo), pless than 0.001
• Distant wart clearance: 42% of untreated warts cleared (immunological memory)
• Superior to intralesional PPD (purified protein derivative)

5. HPV Genotype and Treatment Response (Bruggink et al., 2013) [13]

• HPV-1: 40% clearance at 2 years (resistant to treatment)
• HPV-2/4: 80% clearance at 2 years (more responsive)
• HPV genotype is independent predictor of treatment success

6. Duct Tape Occlusion (Abdel-Latif et al., 2020) [20]

• Silver duct tape occlusion: 60% clearance vs 20% control (pless than 0.05)
• Mechanism unclear (maceration, immune stimulation, mechanical debridement)
• Inexpensive, non-invasive adjunct

Natural History Studies:

7. Spontaneous Resolution of Plantar Warts (García-Oreja et al., 2024) [5]

• 65% spontaneous clearance at 2 years in children
• HPV-1 warts: Slower clearance (40% at 2 years)
• HPV-2/4 warts: Faster clearance (80% at 2 years)

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11. Examination Focus (Viva Questions and Model Answers)

Exam Detail: ### Viva Question 1: Diagnosis and Differential Diagnosis

Examiner: "A 14-year-old boy presents with a painful lesion on the sole of his foot. How would you differentiate a plantar wart from a corn?"

Model Answer:

"I would use a systematic approach to differentiate plantar warts from corns, focusing on three key diagnostic features:

1. Dermatoglyphics (Skin Lines)—the most important distinguishing feature:

• Plantar wart: Skin lines are interrupted and do not cross the lesion
• Corn: Skin lines are preserved and continue across the lesion

2. Surface Appearance:

• Wart: Black dots (thrombosed capillaries) visible, especially after gentle paring of the hyperkeratotic surface
• Corn: Translucent central core, no black dots

3. Pain Pattern:

• Wart: Tender on lateral compression (pinch test)—squeezing from the sides causes sharp pain
• Corn: Tender on direct vertical pressure

I would also consider the clinical context: warts are more common in children and adolescents, often associated with swimming pool exposure, and may be multiple (mosaic pattern). Corns typically occur at specific pressure points (e.g., metatarsal heads) and are related to footwear or gait abnormalities.

If the diagnosis remains uncertain, gentle paring of the surface would reveal black dots in a wart, whereas a corn would show a translucent central core."

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Viva Question 2: Natural History and Treatment Rationale

Examiner: "What is the natural history of plantar warts, and how does this inform your treatment approach?"

Model Answer:

"The natural history of plantar warts is characterized by a high rate of spontaneous resolution, particularly in children. Studies show that approximately 65-78% of warts in children resolve spontaneously within 2 years without any treatment [Cochrane review, meta-analyses].

This natural history has important implications for management:

1. Watchful Waiting is a Valid First-Line Approach:

• For asymptomatic warts in children, observation without treatment is evidence-based
• The British Association of Dermatologists recognizes this as an acceptable first-line strategy

2. Patient-Centered Decision-Making:

• Treatment should be offered based on symptoms (pain, functional impairment), patient preference, and cosmetic concerns
• No treatment has 100% efficacy, and all have potential adverse effects (pain, scarring, hypopigmentation)

3. Factors Affecting Spontaneous Clearance:

• Age: Children have higher clearance rates than adults (65-78% vs 30-40% at 2 years)
• HPV genotype: HPV-1 (deep myrmecia warts) have lower clearance (40% at 2 years) compared to HPV-2/4 (superficial mosaic warts, 80% at 2 years)
• Immunosuppression: Transplant recipients have very low spontaneous clearance (less than 10%)

4. Stepwise Treatment Approach:

• Given the high spontaneous resolution rate, I would start with the least invasive, most cost-effective treatment (salicylic acid), escalating only if there is no response after 12 weeks.
• I would avoid surgical excision due to high recurrence rates (30-50%) and risk of painful scarring on the plantar surface.

In summary, understanding the natural history allows for shared decision-making and avoids unnecessary aggressive treatments in a self-limiting condition."

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Viva Question 3: HPV Genotype and Clinical Significance

Examiner: "How does HPV genotype influence the clinical presentation and treatment of plantar warts?"

Model Answer:

"HPV genotype has significant clinical implications for both presentation and treatment response:

HPV-1 (Myrmecia Warts):

• Prevalence: 60-65% of plantar warts
• Clinical features:
  • Deep, endophytic growth pattern ("myrmecia" = ant hill in Greek)
  • Solitary, well-demarcated lesions
  • Highly keratotic with central depression
  • Markedly painful due to deep dermal extension compressing nerve endings
  • Prominent black dots (thrombosed capillaries)
• Natural history: Lower spontaneous clearance (40% at 2 years vs 80% for HPV-2)
• Treatment response: More resistant to standard treatments (salicylic acid, cryotherapy)

HPV-2 and HPV-4 (Mosaic Warts):

• Prevalence: 10-20% (HPV-2), 5-10% (HPV-4)
• Clinical features:
  • Superficial, exophytic growth pattern
  • "Mosaic pattern: Clusters of multiple small warts (2-5 mm) confluent into plaques"
  • Less painful than HPV-1 (superficial location)
  • Often on non-weight-bearing areas (arch, heel)
• Natural history: Higher spontaneous clearance (80% at 2 years)
• Treatment response: More responsive to first-line treatments

Clinical Significance:

1. Prognostication: HPV-1 warts require more aggressive or prolonged treatment
2. Patient counseling: HPV-1 patients should be counseled that spontaneous resolution is less likely and treatment may take longer
3. Treatment selection: Consider earlier escalation to immunotherapy (Candida antigen, DPCP) for recalcitrant HPV-1 warts
4. Genotyping: Not routinely performed clinically, but research tool—may become clinically useful in the future to guide treatment

Bruggink et al. (2013) demonstrated that HPV genotype is an independent predictor of treatment response, with HPV-1 associated with lower clearance rates across all treatment modalities."

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Viva Question 4: Management of Recalcitrant Warts

Examiner: "A 35-year-old immunocompetent patient has a plantar wart that has failed 12 weeks of salicylic acid and 6 sessions of cryotherapy. What are your next steps?"

Model Answer:

"This represents a recalcitrant plantar wart—defined as failure to respond to first- and second-line treatments over 6 months. My approach would be:

1. Reassess Diagnosis:

• Re-examine the lesion to confirm it is indeed a plantar wart (not a corn, foreign body granuloma, or rare differential like amelanotic melanoma)
• Check for atypical features: rapid growth, ulceration, unusual pigmentation
• If uncertain, perform punch or shave biopsy to exclude mimics (especially if considering more aggressive treatment)

2. Review Treatment Adherence and Technique:

• Was salicylic acid applied correctly? (Daily application, adequate debridement, occlusion, 12-week duration)
• Was cryotherapy adequate? (Sufficient freeze duration, adequate freeze-thaw cycles, pre-treatment debridement)

3. Consider HPV Genotype as a Factor:

• Likely HPV-1 (myrmecia type)—more resistant to treatment
• Counsel patient that this genotype has lower clearance rates

4. Third-Line Treatment Options:

I would discuss the following evidence-based options:

A. Intralesional Immunotherapy (Preferred):

• Candida antigen (0.1-0.3 mL intralesional every 3-4 weeks, max 3-5 sessions)
• Mechanism: Stimulates cell-mediated immunity against HPV
• Efficacy: 70-80% clearance (RCT: 74% vs 20% placebo, Nofal et al. 2022)
• Advantage: Distant wart clearance (40% of untreated warts also clear due to systemic immune response)
• Disadvantage: Painful injection, requires multiple sessions

B. Contact Sensitization (DPCP):

• Diphencyprone topical application (sensitization phase → weekly challenge)
• Efficacy: 60-80% in recalcitrant warts
• Advantage: Immunological memory (lower recurrence)
• Disadvantage: Requires specialist (dermatology), prolonged treatment (3-6 months)

C. Intralesional Bleomycin:

• 0.1% bleomycin injection (0.1-0.2 mL per wart)
• Efficacy: 60-95% (wide variability in studies)
• Advantage: Single session (may repeat if needed)
• Disadvantage: Very painful, risk of Raynaud's phenomenon, scarring

D. Combination Therapy:

• Continue salicylic acid + add duct tape occlusion (inexpensive adjunct—60% clearance in studies)
• Salicylic acid + monthly cryotherapy (may have additive effect)

5. What I Would Avoid:

• Surgical excision: High recurrence (30-50%), risk of painful scar on plantar surface—last resort only
• Laser ablation: Expensive, variable efficacy, scarring risk—not routinely recommended

6. My Preferred Approach: I would recommend intralesional Candida antigen immunotherapy as the next step, given its high efficacy (74% RCT data), systemic immune benefit (distant wart clearance), and relatively low recurrence rate. I would counsel the patient that this requires 3-5 sessions over 3-6 months and can be painful, but offers the best evidence-based chance of clearance for recalcitrant warts.

If Candida immunotherapy fails, I would refer to dermatology for consideration of DPCP contact sensitization."

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Viva Question 5: Immunosuppressed Patient

Examiner: "How does your approach to plantar warts differ in an immunosuppressed patient, such as a renal transplant recipient?"

Model Answer:

"Plantar warts in immunosuppressed patients present unique challenges and require a modified management approach:

1. Epidemiology and Natural History:

• Prevalence: 50-90% of transplant recipients develop cutaneous warts (vs 7-12% general population)
• Spontaneous clearance: Very low (less than 10% at 2 years vs 65-78% in immunocompetent children)
• Clinical features: Multiple, extensive, recalcitrant warts; often mosaic patterns
• Malignant potential: Increased risk of squamous cell carcinoma (SCC) arising in chronic warts (HPV types overlap with oncogenic cutaneous HPV)

2. Modified Management Approach:

A. Lower Threshold for Treatment:

• I would NOT recommend watchful waiting (low spontaneous clearance)
• Early aggressive treatment to prevent extensive disease

B. First-Line Treatment:

• Salicylic acid: Still first-line, but expect lower efficacy (30-50% vs 70-75% in immunocompetent)
• Cryotherapy: Second-line, but also less effective

C. Earlier Escalation to Advanced Therapies:

• Consider intralesional immunotherapy (Candida antigen, MMR) earlier (after 3 months first-line failure, not 6 months)
• Rationale: Despite immunosuppression, local immune stimulation can still be effective
• Efficacy: Reduced compared to immunocompetent patients, but still beneficial (40-60% clearance)

D. Systemic Therapies (Specialist Use):

• Oral retinoids (acitretin): Off-label use for extensive warts in transplant recipients
  • "Mechanism: Antiproliferative effect on keratinocytes"
  • "Dose: 0.5-1 mg/kg/day (requires specialist dermatology input)"
  • "Efficacy: Moderate (30-50% improvement in wart burden)"
  • "Adverse effects: Teratogenic, hepatotoxic, mucocutaneous side effects"
• Optimize immunosuppression: If medically feasible, reduce immunosuppressive load (in consultation with transplant team)

E. Surveillance for Malignancy:

• Low threshold for biopsy of atypical lesions (rapid growth, ulceration, bleeding, non-response to treatment)
• Educate patient on SCC risk and self-monitoring
• Regular dermatological surveillance (6-12 monthly)

F. Prevention:

• Sun protection (UV exposure increases SCC risk in immunosuppressed patients with HPV infection)
• Avoid barefoot walking in communal areas (reduce viral load)

3. Multidisciplinary Approach:

• Collaborate with transplant team (optimize immunosuppression balance)
• Dermatology input for extensive/refractory disease
• Consider HPV vaccination (experimental—no licensed vaccine for cutaneous HPV, but under investigation)

4. Key Differences Summary:

In summary, immunosuppressed patients require more aggressive, earlier treatment, lower threshold for biopsy, and long-term surveillance for malignant transformation."

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12. Patient/Layperson Explanation

What Are Plantar Warts?

Plantar warts (also called verrucae) are small, rough growths on the soles of your feet caused by a virus called the Human Papillomavirus (HPV). They are very common and usually harmless. The word "plantar" refers to the sole of the foot.

How Do You Get Them?

You catch the virus through direct contact with someone who has warts, or by walking barefoot on contaminated surfaces like:

• Swimming pool floors
• Communal showers (gyms, spas)
• Changing room floors

The virus enters through tiny breaks in your skin (like small cuts or cracks). If your skin is wet and soft (from swimming or sweating), the virus can get in more easily.

What Do They Look Like?

Plantar warts have some unique features:

• Flat, rough patches on the sole of your foot (they grow inward due to pressure from walking)
• Small black dots in the center (these are tiny blood vessels, not dirt!)
• Interruption of skin lines (the fingerprint-like ridges on your foot stop at the wart—this is how doctors tell warts apart from corns)

Do They Hurt?

Sometimes, yes. Warts can be painful when you walk, especially if they are on a weight-bearing part of your foot (like the ball or heel). They hurt more when you squeeze them from the sides (pinch) rather than when you press directly on top—this is called the "pinch test."

Do I Need Treatment?

Not always! Here's the good news:

• Most warts go away on their own without any treatment, especially in children. About 2 out of 3 warts disappear within 2 years.
• If your wart doesn't hurt and isn't bothering you, it's perfectly fine to just watch and wait.

You might want treatment if:

• The wart is painful when you walk
• It's affecting your daily activities (sports, wearing shoes)
• You're embarrassed by it (cosmetic reasons)
• You've had it for a long time and it's not going away

What Are the Treatment Options?

1. Salicylic Acid (First Choice)

• You can buy this at the pharmacy (without a prescription)
• It's a liquid or gel that you apply to the wart every day
• It works by softening and removing the hard skin
• How to use it:
  1. Soak your foot in warm water for 10-15 minutes
  2. Gently rub the wart with a pumice stone to remove dead skin
  3. Apply the salicylic acid to the wart (avoid normal skin)
  4. Cover with a bandage or duct tape overnight
  5. Repeat every day for at least 12 weeks
• Success rate: About 7 out of 10 people see their wart clear up

2. Freezing (Cryotherapy)

• Done by a doctor or nurse
• They spray liquid nitrogen (very cold!) on the wart to freeze it
• This destroys the wart tissue
• You need to come back every 2-3 weeks for repeat sessions (usually 4-6 times)
• Side effects: It can be painful, and may cause blistering or temporary discoloration of your skin

3. Other Treatments (For Stubborn Warts) If your wart doesn't go away with salicylic acid or freezing, your doctor might suggest:

• Immunotherapy: An injection into the wart that stimulates your immune system to fight the virus
• Duct tape: Covering the wart with duct tape (surprisingly, this works for some people!)
• Laser or surgery: Rarely needed (last resort)

How Can I Prevent Spreading Warts?

• Wear flip-flops in communal showers, swimming pools, and gym changing rooms
• Don't share towels, socks, or shoes
• Cover your wart with a waterproof plaster when swimming
• Keep your feet dry (the virus spreads more easily on wet skin)
• Don't pick or scratch your wart (this can spread the virus to other parts of your foot)

When Should I See a Doctor?

See your doctor or podiatrist if:

• You're not sure if it's a wart (it could be something else)
• The wart is very painful or bleeding
• You have diabetes or poor circulation (don't treat warts at home)
• The wart looks unusual (different color, rapidly growing)
• You've tried over-the-counter treatment for 12 weeks and it's not working

Key Takeaways

✅ Plantar warts are caused by a virus (HPV) and are very common
✅ They usually go away on their own within 2 years (especially in children)
✅ Treatment is optional—only needed if the wart is painful or bothersome
✅ Salicylic acid (from the pharmacy) is the best first treatment
✅ Prevent spreading by wearing flip-flops in communal areas and covering your wart
✅ Don't worry—warts are harmless and not a sign of poor health!

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13. References

Primary Guidelines

1. British Association of Dermatologists. Guidelines on the Management of Cutaneous Warts (2014).

Systematic Reviews and Meta-Analyses

2. Witchey DJ, Witchey NB, Roth-Kauffman MM, Kauffman MK. Plantar Warts: Epidemiology, Pathophysiology, and Clinical Management. J Am Osteopath Assoc. 2018 Feb 1;118(2):92-105. PMID: 29379975

3. Bristow I, Tay W. Paediatric Cutaneous Warts and Verrucae: An Update. Int J Environ Res Public Health. 2022 Dec 7;19(24):16399. PMID: 36554279

4. Al Aboud AM, Nigam PK. Wart. StatPearls [Internet]. 2025 Jan. PMID: 28613701

5. García-Oreja S, Álvaro-Afonso FJ, Sevillano-Fernández D, et al. Does HPV biotype influence the characteristics and evolution of plantar warts? J Evid Based Med. 2024 Mar;17(1):53-59. PMID: 38305569

6. Stefanaki C, Ieronymaki V, Kontochristopoulos G, et al. Cryotherapy versus imiquimod 5% cream combined with a keratolytic lotion in cutaneous warts in children: A randomized study. J Dermatolog Treat. 2016;27(2):130-4. PMID: 25886088

7. Kwok CS, Gibbs S, Bennett C, et al. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012 Sep 12;(9):CD001781. PMID: 22972052

8. García-Oreja S, Álvaro-Afonso FJ, García-Álvarez Y, et al. Topical treatment for plantar warts: A systematic review. Dermatol Ther. 2021 Jan;34(1):e14621. PMID: 33263934

9. García-Oreja S, Álvaro-Afonso FJ, Sevillano-Fernández D, et al. Efficacy of cryotherapy for plantar warts: A systematic review and meta-analysis. Dermatol Ther. 2022 Jun;35(6):e15495. PMID: 35365922

10. Chanal J, Tramis C, Koopmansch C, et al. A multicentre pragmatic randomized controlled trial comparing 50% salicylic acid, liquid nitrogen, 5% 5-fluorouracil cream, and 5% imiquimod cream in previously treated plantar warts. The VRAIE (VeRrues plAntaIres en villE) study. Ann Dermatol Venereol. 2025 Sep;151(3):103908. PMID: 40743833

Randomized Controlled Trials

11. Nofal A, Salah E, Nofal E, Youst J. Intralesional immunotherapy for multiple recalcitrant plantar warts: Candida antigen is superior to intralesional purified protein derivative. Dermatol Ther. 2022 Jun;35(6):e15500. PMID: 35285995

12. Ahn CS, Huang WW. Imiquimod in the treatment of cutaneous warts: an evidence-based review. Am J Clin Dermatol. 2014 Oct;15(5):387-99. PMID: 25186654

13. Bruggink SC, de Koning MN, Gussekloo J, et al. HPV type in plantar warts influences natural course and treatment response: secondary analysis of a randomised controlled trial. J Clin Virol. 2013 Jul;57(3):227-32. PMID: 23518443

14. Laurent R, Kienzler JL, Croissant O, Orth G. Two anatomoclinical types of warts with plantar localization: specific cytopathogenic effects of papillomavirus. Type I (HPV-1) and type 2 (HPV-2). Arch Dermatol Res. 1982;274(1-2):101-11. PMID: 6299203

15. Sterling JC, Gibbs S, Haque Hussain SS, et al. British Association of Dermatologists' guidelines for the management of cutaneous warts 2014. Br J Dermatol. 2014 Oct;171(4):696-712. PMID: 25273231

Special Populations and Complications

16. Harwood CA, Proby CM. Human papillomaviruses and non-melanoma skin cancer. Curr Opin Infect Dis. 2002 Apr;15(2):101-14. PMID: 11964900

17. Azim AA, Abdel-Latif AA, Ramadan A. Local expression of tumor necrosis factor-alpha and interleukin-4 mRNA in different types of warts. Egypt J Immunol. 2004;11(2):127-32. PMID: 15724382

Advanced Therapies

18. Gamil HD, Saad AA, Elbendary A, Ragheb M. Combined therapy of plantar warts with topical bleomycin and microneedling: a comparative controlled study. J Dermatolog Treat. 2020 May;31(3):310-315. PMID: 31096794

19. Zschocke I, Schöffski O, Blum A, Orfanos CE, Augustin M. [Efficacy and benefit of a 5-FU/salicylic acid preparation in the therapy of common and plantar warts--systematic literature review and meta-analysis]. J Dtsch Dermatol Ges. 2004 Mar;2(3):196-202. PMID: 16281635

20. Abdel-Latif AA, Sanad EM, Abd Elaziz KM, Kandeel AH. Silver duct tape occlusion in treatment of plantar warts in adults: Is it effective? Dermatol Ther. 2020 May;33(3):e13383. PMID: 32223010

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