What is an anogenital wart?
An anogenital wart is a common superficial skin lesion in the anogenital area caused by specific human papillomavirus (HPV) types. Anogenital warts are also called condyloma acuminatum, genital warts, and venereal warts.
What causes anogenital warts?
Anogenital warts are an infection caused by specific human papillomavirus types, most commonly HPV types 6 and 11. Warts will usually appear three to six months after infection but they may appear months or even years later. Anogenital warts are usually a sexually transmitted infection (STI).
What is a human papillomavirus?
Human papillomaviruses (HPV) are a large family of species-specific related double-stranded DNA viruses.
- There are more than 150 different HPV types; at least 40 can infect the anogenital area. Other types cause warts on other areas of skin.
- At least 75% of sexually active adults have been infected with at least one type of anogenital HPV at some time in their life.
- HPV infects keratinocytes in the skin and epithelial cells in mucosa and stimulates them to proliferate, causing a visible lesion.
- HPV infection can be latent, not developing into visible warts. Subclinical infection may show up on a cervical smear.
- Some HPV types cause anogenital cancer. These types are also contagious.
Who gets anogenital warts?
As anogenital warts are usually sexually acquired, they are most commonly observed in young adults between the ages of 15 and 30 years. [see Sexually acquired human papillomavirus] They are highly contagious. However, anogenital warts are rare in people who have been vaccinated against the benign HPV types in childhood before beginning sexual activity. Anogenital warts have been reported in a number of studies to be more common in males than females.
Patients who are immunocompromised due to drug-induced immunosuppression or HIV infection are at particular risk of acquiring HPV and developing anogenital warts.
Anogenital warts can also affect infants and young children. The virus may be acquired during birth or from the hands of carers.
How is HPV transmitted?
Visible anogenital warts and subclinical HPV infection nearly always arise from direct skin to skin contact.
- Sexual contact. This is the most common way amongst adults.
- Transmission is more likely from visible warts than from subclinical or latent HPV infection.
- Oral sex. HPV appears to prefer the genital area to the mouth.
- Vertical (mother to baby) transmission through the birth canal.
- Auto (self) inoculation from one site to another.
What are the clinical features of anogenital warts?
An anogenital wart is a flesh coloured papule with a folded irregular surface a few millimetres in diameter. Warts may join together to form plaques up to several centimetres across. A linear pattern may be seen if the virus has been inoculated along a scratch or tear in the skin. Symptoms associated with anogenital warts can include:
HPV infection may occur in the following anogenital sites:
The same HPV types can also be found in lesions around the lips, the oral mucosa or conjunctiva. [see Squamous cell papilloma]
What are the complications of anogenital warts?
Anogenital warts are contagious and spread particularly to sexual partners.
Anogenital warts can enlarge and multiply during pregnancy which may then interfere with vaginal delivery. HPV can be transmitted to the baby resulting in recurrent respiratory papillomatosis in the infant.
Anogenital warts can impact psychosexual functioning and quality of life. [see Psychosocial factors in dermatology]
How are anogenital warts diagnosed?
Anogenital warts are usually diagnosed clinically.
In some circumstances, researchers and clinicians may wish to confirm the presence or absence of HPV. One commercially available qualitative test for HPV is the COBAS 4800 Human Papillomavirus (HrHPV) Test, which evaluates 14 high-risk (HR oncogenic) HPV types.
What is the differential diagnosis of anogenital warts?
Normal anatomical structures may be confused with warts. These include:
- Pearly papules (these are in a ring around the glans of the penis )
- Sebaceous glands on the labia (known as "Fordyce spots")
- Vestibular papillae (the fronds found in the opening to the vagina).
Seborrhoeic keratoses are often observed in the anogenital area of older adults.
Anogenital squamous cell carcinoma is an important differential diagnosis to consider as the high-risk and low-risk HPV types are both STIs and can be transmitted together.
What is the treatment for anogenital warts?
Prevention of HPV infection: Human papillomavirus vaccine
HPV vaccination is most effective when offered at a young age, before the onset of sexual activity. However, girls who are already sexually active may not have been infected with the types of HPV covered by the vaccine and may still benefit from vaccination. Women who receive a HPV vaccine should continue to participate in cervical screening programmes.
HPV vaccines are also effective in boys. Vaccination of boys is recommended to reduce transmission of HPV to unvaccinated females. It also reduces the incidence of cancers in males related to HPV infection.
Prevention of anogenital HPV transmission
Transmission of anogenital warts to a new sexual partner can be reduced but not completely prevented by using condoms. Condoms do not prevent all genital skin-to-skin contact, but they also protect against other sexually transmitted infections.
Treatment options for anogenital warts
- Self-applied treatments at home
- Treatment at a doctor's surgery or medical clinic.
Self-applied topical treatments
To be successful the patient must identify and reach the warts, and follow the application instructions carefully. Available treatments include:
Treatments provided at a medical clinic
- Podophyllin resin
- Trichloroacetic acid applications
- Curettage and scissor or scalpel excision
- Laser ablation
What is the outcome of anogenital warts?
Anogenital warts can resolve spontaneously or in response to treatment. Despite apparent resolution of anogenital warts, the virus can persist in a latent or subclinical form. Recurrence is therefore very common, particularly in males.