Tumours of epidermis caused by DNA-containing human papillomavirus (HPV). Affects up to 10% of population – higher in children – peak incidence 12-16 years.

HPV infection is highly specific for the epidermic. Viral particles are only found in stratum granulosum and keratin layers of skin. Virus enters skin after contact with infected individual or recently shed virus kept alive in moist warm environment (eg showers, swimming pools, shared facilities), but can remain alive on inanimate surfaces for unknown amounts of time – usually enters via site of recent micro-trauma. Autoinoculation causes local spread. Incubation is unknown – can be from a few weeks or up to 1 year.
60+ genotypes of HPV have been documented.
Commonly get hyperplasia and hyperkeratosis of the epidermis.

Clinical features:
In earliest stages  appear as small vesicle  progresses to disruption of normal skin lines  ‘cauliflower’ appearance with red spots within lesion (these are thrombosed blood vessels).

Verruca vulgaris (plane warts) – most common – start as smooth flesh coloured papule  develop to nodule with rough irregular hyperkeratotic surface; can be single or grouped – usually on hands, but can occur at any site – commonly caused by HPV types 2, 4, 29
Plane warts/flat warts – usually small multiple, flat smooth, papular lesions, slightly darker than surrounding skin – commonly on face, knees and dorsal surface of hands; commonly caused by HPV types 3 & 10.
Plantar warts/verruca pedis – thick, hyperkeratotic lesion; painful if on weightbearing area; appearance is altered by forces of weightbearing; most caused by HPV types 1, 2, 4 or 10.

In the immunocompromised, verrucae are commonly caused by HPV type 8

Differential Diagnosis:
Heloma durum (debridement of verrucae reveals ‘pinpoint’ bleeding and of heloma will reveal ‘nucleus’); healed scar from previous treatment; molluscum contagiosum; eccrine poroma; Bowen’s disease; arsenical keratosis; lichen planus.

Spontaneous remission is common – those that do not resolve tend to proliferate and be infective. Assumed that 30% resolve spontaneous in 3-6 months – 50% over 2 years  may account for controversy over most appropriate method and proliferation of ‘folk’ remedies.

Reasons not to treat Reasons to treat
May be painless and show no signs of spreading May be painful and show signs of spreading
May resolve spontaneously May be cosmetically unacceptable
Treatment can be painful and inconvenient May be a high risk of spreading to other people
Treatment may cause scarring in the area Possibly become more resistant to treatment the longer they are present

Involution of verrucae is considered an immune response – not uncommon for treatment of one to result in resolution of others – serum antibodies have been found

Factors that influence response to treatment:
Age – less successful in older patients
Type – single verruca respond better than mosaic verruca
Number – single lesions disappear faster than multiple
Duration – older lesions more resistant to treatment
Host factors – immune response of individual

Choice of treatment depends on:
• risk to patient
• site
• potential of scaring
• number
• size
• age
• previous treatment
• side effects
• pain
• inconvenience

Treatment modalities:
1) Chemotherapy
a) Acids
i) Salicylic (usually 20-75%)
ii) Lactic
iii) Trichloroacetic
iv) Monochloroacetic
iv) Nitric (usually 70%)
v) Pyrogallic acid
b) Others
i) Podophyllin
ii) Phenol
iii) Silver nitrate

• Surrounding skin is usually masked to prevent spread of acid to normal tissues (eg hole cut in adhesive tape or 95% silver nitrate)
• medicament is applied – overed with tape and protected with felt pad – area must generally be kept dry
• alternatively patient applies medicament daily if required
• necrotic tissue is debrided at subsequent visits until resolution
• can be time consuming and depth of penetration of acid can not be controlled

2) Cryotherapy (uses cold temperatures to destroy tissues)
a) Liquid nitrogen (-196°C)
b) Cryotherapy units

• can be painful, but safe  can observe growth of the border of the ‘ice ball’ in the tissues
• generally consider that the more rapid the freezing, the more effective

• apply padding to relieve discomfort

3) Surgical
a) Electrocautery
• high frequency current heat  tissue destruction
• need local anaesthetic
• 4 main methods of administration:
• Fulguration – probe passed over lesion at distance of 2cm  current arcs  superficial necrosis  remove with scalpel and reapply
• Desiccation – probe is in contact with lesion  deeper necrosis
• Electrosection – cutting of tissues
• Electrodessication and coagulation – use of special unit
b) Curettage
• Volkmann spoon is used to ‘scoop’ out verrucae
• some risk of scarring
• particularly indicated in verrucae resistant to other treatments
c) Excision
• surgical excision
d) Laser

4) Immunotherapy
• Could have great potential (less/no scaring)
Cimetidine (H2 receptor blocker to decrease stomach acid production). Stimulation of H2 receptors in skin  increase in suppressor T-cell activity, decreased basophil histamine release, decrease lymphotoxity, decreased neutrophil and eosinophil chemotaxis  useful response in viral conditions. Studies on use of verrucae show mixed and inconsistent results. Has a number of side effects, including increased risk for delayed type hypersensitivity reactions.

5) Others
Many clinicians claim (often dogmatically) success for their “pet” treatment. Very few clinical trials have compared treatments. These treatments may be supported by further work.

a) For resistant mosaic type verrucae – twice daily dose of 15 000 units of Vitamin A (mild exfoliative) and 15mcg zinc (increases cell turnover) (Gary Dockery, personal communication).

6) Hypnosis and folk remedies:
Hypnosis and suggestion have been reported as being successful – may be due to secondary immune response.
Folk remedies probably work due to timing of use coincides with spontaneous resolution – or some psychological interaction with the immune response.

Previous scarring from injudicious treatment of heloma durum misdiagnosed as a verrucae or from ‘overzealous management of verrucae –

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Verrucous Skin Lesions on the Feet in Diabetic Neuropathy
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