Verruca

Verrucas or plantar warts are hyperkeratotic lesions found particularly over the pressure areas of the feet (heel and ball). They are usually self-limiting but may be treated if symptomatic.

• Half disappear within a year
• 2/3 disappear after 2 years
• Remaining 1/3 more resistant and persistent

They are caused by the human papilloma virus (types 1 and 2 mainly but also 4). They affect epithelial cells causing small rough papules. Replication of the virus within the epithelial cells causes a proliferative reaction and formation of plaque or papule. Incubation is very variable ranging from 1 month up to 2 years.

• They are spread by person to person contact
• Use of communal showers is associated with higher rates of plantar warts²
• Infection is more likely if skin is macerated
• Scratching, nail biting, finger sucking and shaving all encourage autoinoculation of viral warts
• They should not be used as reason to stop children swimming as learning to swim is important in the National Curicculum and helps prevent death from drowning^3,4
• They may be covered (with waterproof plasters or socks) when swimming but this can stigmatise children and there is no evidence that these measures prevent spread.⁵

Data is limited, but:

• They are widespread and some report as many as 10% of the population affected at any time
• Most people get them at some time in their lives
• They appear to affect women marginally more than men
• They are more common with peak incidence in children and teenagers (affect about 4-5%)
• They are uncommon in infants
• They are more common particularly on the hands in eczema and with certain occupations (butchers, abattoir workers, engineers, office workers)

• History
  • They may cause pain particularly with walking
  • Occasionally leg or back pain may result from altered posture or gait disturbance
  • May be found in other family members
  • More common in:
    • Certain occupations
    • Atopic eczema
    • Impaired cellular immunity (usually numerous and resistant):
      • Long term immunosuppressant usage
      • AIDS
      • Transplant patients
      • Lymphomas and leukaemias
• Examination
  • Firm, hyperkeratotic lesions
  • May have minor pinpoint petechiae centrally within the lesions
  • Usually found over pressure areas
  • Flat because of pressure
  • May fuse with surrounding warts (mosaic warts)
  • May occasionally be difficult to differentiate from other conditions (see differential diagnosis below)

• Corns: these are inflammed and painful. Paring corns reveals pearly sections of keratin.
• Calluses: these are thick and painless patches of hard skin.
• Black heel: patches hard skin with ruptured capillaeries.
• Verrucous squamous cell carcinoma: this should be considered if longstanding. They invade the dermis but are slow growing and rarely metastasise.

None usually required or appropriate. Distinguishing them from corns may require paring of the keratin as above. Bloods to check for causes of immunodeficiency may be required in unusually widespread or resistant cases.

Usually none. However consider drugs and diseases affecting particularly cellular immunity.

• Education about the natural history
• Usually no treatment if not painful
• More likely to want or need treatment if:
  • Painful
  • Immunosuppressed
  • Resistant cases (present for 2 years or more)
  • Patient choice in full knowledge of natural history
• Choices of treatment include:
  • Salicylic acid preparations:
    • Several brands available over the counter
    • Plasters
    • Colloiden
    • Gel
    • Paint
    • Combined with podophyllum resin
  • Formaldehyde and glutaraldehyde preparations-unpleasant and used less often
  • Cryotherapy- usually 2 to 4 treatments (using a 1 minute freeze thaw cycle after paring away excess keratin) 4 weeks apart
  • Rarely used methods include surgical excision, curettage, 5-fluorouracil, interferons, photodynamic therapy and bleomycin injection

A recent study suggests that salicylic acid preparations (over the counter use) was the most cost effective treatment and that nurse-administered cryotherapy was more cost-effective than GP-administered cryotherapy.⁷ Generally speaking there is a lack of evidence for efficacy and cost effectiveness of treatments.⁸ Banana skins, witchcraft and hypnosis also have their advocates.^9,10

• Secondary to treatment:
  • Pain
  • Infection
  • Scars and keloid formation
• Psychological
• Malignant change: extremely rare especially with normal immunity. Rarely occurs but be aware of the possibility in patients who are immunocompromised (for example transplant patients).

It should be borne in mind that:

• Treatment failure is common
• Verrucas may be impossible to get rid of in the immunocompromised patient
• Two thirds will disappear after 2 years without treatment
• 90% of warts present at age 11 years will be gone by age 16 years

There is no evidence that using verruca socks prevents spread and the possible stigmatising effect of wearing such socks suggests use should be discouraged.