Wart is caused by a viral infection, human papillomavirus (HPV). It can affect the skin and genital mucosa, both in men and women.

Cause

There are more than 100 types of HPV with different types of clinical presentations. The common warts are usually due to HPV type 2 and 4 (most common), followed by type 1, 3, 27, 29, and 57. Deep palmoplantar warts are due to HPV type 1 (most common), followed by type 2, 3, 4, 27, 29, and 57. Flat warts are due to HPV type 3, 10, and 28.

An individual can be infected with warts through skin contact. It can also spread from one part of the body to the other parts of the body by autoinnoculation. The risk of infection is higher if the skin barrier surface is abnormal.

There are several types of HPV that can cause cancer such as HPV type 6, 11, 16, 18 and 35. Cancer transformation can occur if it involves the genital mucosa or occur in immunocompromised individuals.

Clinical presentations

Warts can affect any age group but children and adolecents from the age of 12 to16 years old are commonly infected. There are different types of warts such as common warts, filiform warts, genital warts, flat warts and deep palmoplantar warts.

The common wart is also called verruca vulgaris (Figure 1). It has a rough surface and the size can range from 1mm to 1 cm. The filiform wart (Figure 2) usually affects the face and eyelids but it can occur elsewhere. Deep palmoplantar warts (Figure 3) usually occur on the plantar surface of weight-bearing areas, near the toes and heel. Flat wart (Figure 4) has a smooth surface or slightly rough surface and the size range from 1 to 5mm. There can be more than just a few warts and commonly involve the face, hand and feet.

Figure 1: Common warts on the hand	Figure 2: Filiform  warts
Figure 3: Palmoplantar Warts	Figure 4: Plane warts affecting the hand

Treatment

There are various types of treatment and it is quite difficult to clear warts completely. There may be several attempts and failures with treatment. Without treatment, 65% can regress spontaneously within 2 years. However, without treatment, warts may enlarge or spread to other areas.

Various types of treatment available include:

1. Salicylic acid. This can be purchased and applied to the affected area. It is effective in 70 to 80% of patients.
2. Cryotherapy with a temperature of -196ºC can be used and will need repeated treatment every 1-4 weeks until cleared.
3. Podophyllin is used specifically to treat genital warts and can only be applied by doctors or trained health personnels.
4. The use of laser is limited due to its’ high risk to the operator as it can be inhaled through the airway.
5. Trichloroacetic acid can also be used for genital warts and can only be applied by doctors or trained health personnels.
6. Imiquimod can modulate the immune response and can be used for genital warts.

References

1. Silverberg NB. Human papillomavirus infections in children. Curr Opin Pediatr. Aug 2004;16(4):402-9.
2. Bellew SG, Quartarolo N, Janniger CK. Childhood warts: an update. Cutis. Jun 2004;73(6):379-84.
3. Goldfarb MT, Gupta AK, Gupta MA, Sawchuk WS. Office therapy for human papillomavirus infection in nongenital sites. Dermatol Clin. Apr 1991;9(2):287-96.
4. Perrett CM, Harwood C, Brown V. Topical 5% imiquimod treatment for refractory cutaneous warts. J Am Acad Dermatol. 2004;50(3):P41.
5. Bourke JF, Berth-Jones J, Hutchinson PE. Cryotherapy of common viral warts at intervals of 1, 2 and 3 weeks. Br J Dermatol. Mar 1995;132(3):433-6.
6. Sloan K, Haberman H, Lynde CW. Carbon dioxide laser-treatment of resistant verrucae vulgaris: retrospective analysis. J Cutan Med Surg. Jan 1998;2(3):142-5.