|August 2011 · Vol. 23, No. 8
External genital warts: diagnosis and burden of disease
Barbara Dehn, RN, MS, NP
Nurse Practitioner, Women’s Physicians ObGyn Medical Group, Mountain View, CA
Nurse Dehn is a consultant to Hologic, Inc, Ortho-McNeil-Janssen Pharmaceuticals, Inc, and Graceway Pharmaceuticals, LLC; she is a speaker for Bayer HealthCare Pharmaceuticals, Genentech, Roche, Cord Blood Registry, and Abbott Labs; and she is a vendor for Cord Blood Registry.
External genital warts (EGW) are caused by the human papillomavirus (HPV), a highly contagious sexually transmitted infection (STI). HPV infects the basal epithelium via microabrasions and tissue disruption of genital skin/mucosa or oral mucosa.1,2 EGW are only one manifestation of HPV infection; HPV DNA may also integrate into the host genome and may lead to malignant transformation. New clinical practice guidelines from the Centers for Disease Control and Prevention (CDC), Sexually Transmitted Diseases Treatment Guidelines, 2010, provide information and recommendations on EGW.3
TYPES OF HPV
More than 100 types of HPV have been identified to date, with about 40 types infecting the anogenital tract.3 The types are categorized as high or low risk, based on oncogenic potential for causing cervical cancer. The types of HPV that cause EGW are not the same as those that can cause cervical cancer.4
Worldwide, HPV types 16 and 18 are responsible for most cervical cancer and are also associated with other anogenital cancers, including vulvar, vaginal, penile, and anal, as well as some oropharyngeal cancers. HPV types 6 and 11 are nononcogenic, and these low-risk types are the cause of 90% of EGW.3 Tests for HPV types are available but are indicated only for women who are undergoing cervical cancer screening.3
In most cases, HPV infection is asymptomatic, with the immune system rendering HPV undetectable within 2 years.4 HPV infection is highly prevalent, with more than 50% of sexually active people becoming infected at least once (TABLE).4 When oncogenic HPV types persist and do not resolve despite the host’s immune response, an environment for cancer development is created. Co-infection with low- and high-risk types is also possible. Multitype infection increases the risk of persistent infection and acquisition of other HPV types, as well as cytologic abnormalities.
Anogenital HPV is the most common sexually transmitted infection in the United States.
Prevalence of HPV is estimated at 20 million.
An estimated 6 million people are newly infected each year.
About half of all sexually active adults have HPV at some point in their life.
More than 500,000 new cases of EGW are diagnosed annually in the United States.
The incidence of EGW increases every year.
CLINICAL FEATURES OF EGW
The differential diagnosis of EGW includes a number of other conditions, including condyloma lata, molluscum contagiosum, lichen nitidus, seborrheic keratosis, benign and dysplastic nevi, verrucous carcinoma, and micropapillomatosis labialis. The typical appearance of EGW is cauliflower-like, but they may be flat, papular, keratotic with a thick and horny layer, or frond-like (FIGURE). EGW may develop on the vulva, groin, perineum, or perianal skin. They may be asymptomatic, or they may cause anogenital pruritus, burning, and/or dyspareunia. EGW may develop at multiple sites in some patients.
DIAGNOSIS OF EGW
The diagnosis of EGW is mainly accomplished by visual inspection. A biopsy is needed only if the patient is immunocompromised; the diagnosis is unclear; there is a sudden recent growth of lesion(s); or if the EGW are pigmented, indurated, fixed, ulcerated, or bleeding. An acetowhite test for EGW has a low positive predictive value, and the new CDC guidelines recommend against using it for diagnosis.
IMPLICATIONS OF EGW
HPV is communicated through genital contact, usually during vaginal or anal sex, but can also be passed through oral sex. Many, if not most, infected people do not realize they are infected, and therefore, the infection can be passed on to a sex partner without their knowledge. Further complicating this is the long incubation from infection to appearance of symptoms, which can range from 3 weeks to 8 months.
The psychosocial impact of EGW is considerable. It can include anger, depression, and shame. Many patients feel there is a stigma associated with an STI, and this often has a negative impact on their relationships and sexual activity and enjoyment. There may be dyspareunia and fear of transmitting the disease to a partner, as well as fear of the possibility of the HPV infection progressing to cancer.
More than 500,000 new cases of EGW are diagnosed annually in the United States, with the rate increasing every year. EGW cause a substantial psychosocial burden in addition to the clinical burden.
1. Hsueh PR. Human papillomavirus, genital warts, and vaccines. J Microbiol Immunol Infect. 2009; 42(2):101–106.
2. Grm HS, Bergant M, Banks L. Human papilloma-virus infection, cancer & therapy. Indian J Med Res. 2009;130(3):277–285.
3. Workowski KA, Berman S. Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2010. MMWR Recomm Rep. 2010;59(RR-12):1–110.
4. CDC. Genital HPV Infection—Fact Sheet. Available at: www.cdc.gov/std/HPV/STDFactHPV.htm#common. Accessed March 18, 2011.
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