Human papillomavirus (viral warts) - Viral skin infections

Human papillomavirus (viral warts)

Definition

Human papillomavirus (HPV) infections affecting epithelial tissues and mucous membranes.

Aetiology

Human papillomaviruses are double-stranded DNA viruses. Over 70 subtypes are identifiable and different subtypes cause infections at different sites of the body: HPV type 2 causes hand warts, type 1 and 2 cause plantar warts, and various subtypes cause genital warts and anogenital intraepithelial neoplasia. HPV types 16–18 are high-risk subtypes for neoplasia and are associated with cervical and oral cancer. The virus is spread direct by direct contact, anogenital warts, and HPV infection of the cervix may be sexually transmitted.

Clinical features

1.     Common warts are well-demarcated dome shaped papules or nodules with an irregular papilliferous surface. Commonly occur on the back of hands, between fingers and around the nail edge.

2.     Plantar warts (often called verrucae) are seen on the soles of feet particularly in children. They appear as thickened plaques with overlying callous, which may reveal underlying black dots if removed.

3.     Flat warts are smooth-topped papules often multiple and refractory to treatment.

Microscopy

The epidermis is hyperkeratotic and thickened. Infection of keratinocytes in the granular layer results in a vacuolated appearance.

Management

No treatment is universally successful, and as there is a high spontaneous resolution, management may be expectant. Available treatments include topical keratolytics such as salicylic acid, cryotherapy, surgical excision and laser treatments.

Prognosis

Most warts spontaneously resolve over 2 years.