Warts and verrucas

Definition
Warts are benign skin growths caused by infection with certain types of human papillomavirus (HPV). Verrucas are warts that occur on the soles of the feet and are often flat due to pressure from walking.

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Cause and Pathophysiology

• Caused by HPV (different types affect different body sites)

• Virus infects the epidermis, stimulating rapid keratinocyte proliferation

• Spread occurs through direct skin-to-skin contact or indirectly via contaminated surfaces (showers, floors, towels)

• Risk increased in:

  • Children and adolescents

  • Immunocompromised individuals

  • People with skin trauma or maceration (e.g., from wet environments)

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Types

1. Common warts (verruca vulgaris) – rough, raised surface, usually on hands or fingers

2. Plantar warts (verruca plantaris) – on soles of feet, may be painful when walking, often with black pinpoint dots (thrombosed capillaries)

3. Plane warts (verruca plana) – smooth, flat-topped, multiple, often on face or hands

4. Filiform warts – long, narrow projections, often on face or neck

5. Periungual warts – around fingernails or toenails, can distort nail growth

6. Genital warts – sexually transmitted, caused by different HPV strains (not included in “verruca” term)

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Symptoms

• Usually painless (except plantar verrucas, which can be tender with pressure)

• Rough surface, skin-coloured or slightly darker

• May occur singly or in clusters (“mosaic” verrucas)

• Tiny black dots inside lesion (capillary thrombosis) are common

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Diagnosis

• Clinical examination (appearance is usually diagnostic)

• Dermatoscopy may aid diagnosis

• Rarely, biopsy if diagnosis is uncertain or to rule out malignancy

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Treatment
Warts can resolve spontaneously (especially in children), but treatment is considered if they are painful, spreading, or persistent.

Topical treatments

• Salicylic acid preparations (first-line)

  • Concentrations: 17–50% for common/plantar warts

  • Apply daily after soaking and paring down thick skin

  • Continue for up to 12 weeks

• Lactic acid + salicylic acid combination – may be more effective than salicylic acid alone

Physical treatments

• Cryotherapy (liquid nitrogen)

  • Every 2–3 weeks until clearance (usually 3–4 sessions, sometimes longer)

• Electrocautery, curettage, or laser therapy – for resistant cases

• Needling – under local anaesthesia to stimulate immune response (especially for plantar warts)

Immune-modulating treatments (for resistant or multiple warts)

• Topical imiquimod 5% cream (off-label for non-genital warts)

• Intralesional bleomycin or immunotherapy (candida antigen) – in specialist settings

Plantar verruca-specific advice

• Use cushioning or corn pads to reduce pressure and pain while walking

• Wear flip-flops in communal showers and swimming pools to prevent spread

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Prevention

• Avoid sharing towels, shoes, or socks

• Keep feet dry and change socks daily

• Cover warts with waterproof plasters in communal areas

• Do not pick or scratch warts

• Use footwear in public showers/swimming pools

Quick-Reference Clinical Chart – Warts and Verrucas

Type of Wart	Common HPV Strains	Typical Location	Appearance / Features	First-Line Treatment	Alternative / Specialist Treatment
Common wart (Verruca vulgaris)	HPV 2, 4, 27, 57	Hands, fingers, knees	Rough, raised, skin-coloured papules; firm surface	Salicylic acid 17–27% daily after paring	Cryotherapy every 2–3 weeks, curettage, electrocautery
Plantar wart (Verruca plantaris)	HPV 1, 2, 4, 63	Soles of feet	Flat or depressed due to pressure; may have black dots; painful on walking	Salicylic acid 27–50% daily + padding	Cryotherapy, needling, laser therapy, bleomycin injection
Mosaic wart	HPV 2	Soles of feet (clusters)	Multiple small plantar warts merging in patches	Salicylic acid 27–50% + regular paring	Cryotherapy, immunotherapy
Plane wart (Verruca plana)	HPV 3, 10, 28	Face, hands, shins	Smooth, flat-topped, skin-coloured or brown papules; multiple	Salicylic acid low strength (≤17%)	Imiquimod 5% cream, cryotherapy (gentle)
Filiform wart	HPV 1, 2, 4	Face, lips, eyelids, neck	Long, narrow projections; stalk-like	Careful snip excision, curettage	Electrocautery, cryotherapy
Periungual wart	HPV 1, 2, 4, 7	Around nails	Rough growths that may distort nail; painful if extensive	Salicylic acid 17–27% with occlusion	Cryotherapy, surgical removal
Genital wart (Condyloma acuminata)	HPV 6, 11 (low-risk)	Genital and perianal skin	Soft, flesh-coloured, cauliflower-like lesions	Podophyllotoxin, imiquimod 5%, cryotherapy	Surgical excision, laser, electrocautery

Clinical Notes

• Salicylic acid: Apply to clean, soaked skin, pare thick skin before application, protect surrounding skin with petroleum jelly

• Cryotherapy: Typically 10–20 seconds freeze time, repeat at intervals

• Resistant warts may require combination therapy (e.g., salicylic acid + cryotherapy)

• Most warts resolve spontaneously within 1–2 years in immunocompetent individuals, but recurrence is common

• Immunocompromised patients may require prolonged or more aggressive therapy