Cutaneous Warts
Cutaneous warts are benign skin lesions caused by human papillomavirus (HPV) infection of keratinocytes on keratinised skin.
This updated UKMLA guide is based on NICE CKS, which covers common warts, plane / flat warts, plantar warts and filiform warts, including causes, recognition, diagnosis and management.
Causes and Risk Factors
Most cases are caused by HPV types 1, 2, 4, 27 or 57, and plane warts by HPV types 3 or 10. [Ref]
The key takeaway is that high-risk HPV strains (e.g. 16, 18, 31, and 33) do NOT cause cutaneous warts.
Instead, they are primarily associated with cervical cancer and other HPV-related malignancies (e.g. anal cancer, vulval cancer, penile cancer).
Warts are usually spread by direct skin-to-skin contact or indirectly via contact with contaminated floors or surfaces.
Risk factors:
- Skin breaks / damage / microtrauma
- Scratching / picking/ knocking on an existing wart (e.g. warts on fingers may spread widely around the nails in those who bite their nails)
- Occupation involves regular direct handling of meat or fish (higher risk of hand warts)
- Frequent water immersion (e.g. swimming, regular dishwashing)
- Immunocompromised
Clinical Features and Diagnosis
Cutaneous warts are primarily a clinical diagnosis
- Further investigations are not required
- Dermoscopy examination may be helpful if there is diagnostic uncertainty
| Wart type | Appearance |
|---|---|
| Common wart (verruca vulgaris) | The classic cauliflower-like lesion
Usually asymptomatic |
| Flat warts or plane warts (verrucae planae) |
Usually asymptomatic |
| Plantar warts (verrucae plantares) |
May be painful (e.g. on walking) |
| Filiform warts |
Usually asymptomatic |
Malignant transformation of cutaneous warts is rare, but has been reported in immunosuppressed patients.
Lesions may initially have appeared as warts and later transform into squamous cell carcinoma.
Anogenital warts (condylomata acuminata) are considered a separate category from cutaneous warts, as it does NOT occur on keratinised skin.
Management
Referral to dermatology should be considered if ANY of the following:
- Facial wart
- Immunocompromised
- Extensive skin involvement (e.g. mosaic warts)
- Refractory to primary care treatment options
General / Conservative Management
| Patient education | Advise that:
|
| Measures to reduce risk of transmission | Warts are contagious, but the risk of transmission is thought to be low
To reduce the risk of spread to other individuals:
To reduce the risk of auto-inoculation:
|
| Activity exclusion | Children with warts or verrucae should not be excluded from activities (e.g. sports, swimming)
But should take care to minimise transmission |
Indications to Treat
Most cases do NOT require treatment, rationale:
- Most cases are asymptomatic and resolve spontaneously
- This is especially true in children, as warts are more likely to resolve spontaneously, and treatment could be uncomfortable or not tolerated
- Treatment is relatively lengthy and has adverse effects
Consider treatment if ANY of the following:
- Painful wart (e.g. plantar warts and periungual warts)
- Cosmetically unsightly (e.g. on the face and hands)
- Patient requests treatment in cases of persistent warts
Cryotherapy requires several treatments, can be painful at the time of application, and may cause pain, blistering, infection, scarring, and depigmentation.
Topical salicylic acid may require administration for up to 12 weeks and can cause local skin irritation.
Treatment Options
Primary care treatment options (the exact choice depends on what has been tried already and what the patient prefers):
| Treatment option | Description / notes |
|---|---|
| Topical salicylic acid | To be applied for up to 12 weeks
Preferred in younger children |
| Cryotherapy (with liquid nitrogen) | Usually carried every 2-4 weeks until the wart is resolved (up to a maximum of 6 treatments)
Cryotherapy should NOT be used in young children. |
| Combination therapy | Topical salicylic acid being applied between cryotherapy sessions
More likely to be helpful in plantar warts (cryotherapy alone is less likely to resolve it, and more aggressive cryotherapy might be necessary) |
Secondary care options:
- Physical ablation (e.g. surgery, laser, microwave, photodynamic treatment)
- Antimitotic treatments (e.g. topical podophyllin, retinoids, intralesional bleomycin)
- Immunomodulatory treatments
- Topical 5-fluorouracil