Author: Sonam Vadera, final year medical student, University College London, UK. DermNet New Zealand Editor–in–Chief: A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy editor: Gus Mitchell. October 2017.
Human papillomavirus (HPV) is a DNA virus of the papillomavirus family. It is also known as wart virus.
HPV infects the epidermal cells that form the skin, and the epithelial cells that form the anogenital tract and upper respiratory tract. Eight in every ten individuals are estimated to have contracted HPV at some point in their lifetime.
The HPV family has been classified into more than 170 subtypes, denoted by a numerical system.
Various subtypes of HPV preferentially infect epithelial cells and are most often sexually transmitted.
Low–risk subtypes of HPV such as types 6 and 11 are asymptomatic or cause warts and squamous cell papillomas.
There are approximately 13 high–risk subtypes of sexually transmitted HPV. In some cases, these present with precancerous squamous intraepithelial lesions and cancer (squamous cell carcinoma).
Sexually acquired HPV infects both men and women. The highest risk of acquiring HPV is soon after sexual debut.
Risk factors for infection include:
HPV is typically spread via skin–skin contact during vaginal and anal sexual intercourse. HPV can also occasionally be transmitted vertically, from mother to child during birth.
Cutaneous HPV presents as:
Although HPV is the most common sexually transmitted virus, the virus is symptomless in most individuals and the infection resolves by itself.
Persistence of certain subtypes of HPV leads to:
High–risk subtypes HPV 16 and HPV 18 are thought to be responsible for 70% of precancerous and cancerous disease.
Squamous intraepithelial lesions (SIL), also known as intraepithelial neoplasia (IN), are classified by the affected site. Types of SIL include:
HPV is also associated with squamous cell carcinomas of the anus, oropharyngeal tract, vagina, vulva and penis. The most common invasive cancer associated with HPV is cervical cancer.
HPV infection is diagnosed clinically. Genital warts caused by HPV infection show a characteristic presence of koilocytes and can be identified by skin biopsy. Double nuclei may be seen, and the nuclei are often hyperchromatic.
Other methods of diagnosing HPV infection include:
HPV cannot be eliminated, as it incorporates into the genome of the epithelial cells. However, the resultant warts, precancerous and cancerous lesions can be removed.
Treatments may include:
Condoms are an important means to reduce transmission of HPV. They do not completely eliminate the risk.
Most cases of sexually acquired HPV infection may be prevented by vaccination during childhood before the onset of sexual activity.
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