#AskID : Prof Ryan discusses warts

We asked Prof Caitriona Ryan:
‘Viral warts on the fingers are a very common benign lesions caused by infection with human papillomavirus (HPV). They are particularly common in school-aged children, however they may occur at any age. They are more common in those who are immunosuppressed or in paitents with eczema due the defective skin barrier. They recur more commonly in those who smoke.
HPV Infection affects the bottom layer (basal layer) of the epidermis of the skin, causing proliferation of skin cells, thickening of the skin, and production of infectious virus particles, to form a wart. HPV is spread by direct skin-to-skin contact between people or from one site to another site on the same person. Viral warts usually go away on their own but it may take months or sometimes years. The treatments used for warts do not kill the virus itself, but work by removing virus-containing skin. Warts recur rapidly if the virus has not been eradicated completely.

You don’t always need to see a doctor when you have viral warts. Several over-the-counter topical treatments are available at pharmacies which typically contain salicylic acid in the form of solutions, paints, or patches which remove surface skin cells. These are typically applied daily for up to 3 months. It is important to soften the wart by soaking in warm water and to pare the wart with a nail file or pumice stone prior to applying topical treamtents – this helps penetration of the medication through thickened skin to improve the success rate of the treatment.

If over-the-counter treatments are not successful, it may be necessary to visit your GP or Dermatologist, particuarly if the wart is painful, recurrent or if it occurs on the face.

Your doctor may prescribe salicylic acid, 5-Fluoro-uracil, or podophyllin topical treatments. More commonly cryotherapy with liquid nitrogen is used at 1-2 week intervals to cause destruction of the warts. It can be painful and often causes blistering. Typically 2-8 treatments may be required. Sometimes cantharidin is applied by your doctor. This ia substance derived from the blister beetle Cantharis vesicatoria which causes a blister to form on the wart.
This action lifts the wart off the skin. Other topical immunotherapies such as diphencyprone or squaric acid are used to incite a localised allergic contact dermatitis over the wart. Rarely surgery is used to treat com large and resistant warts. Under local anaesthetic, the growth is pared away and the base burned.There has been anecdotal reports of multiple common warts resolving after a patient receives the HPV vaccine even though this is against different subtypes of HPV.