Genital warts are lesions of the skin or mucous membranes of the genitals caused by certain types of human papillomavirus (HPV). Some types of HPV cause flat warts in the cervical canal or anus; these warts can become cancerous. Diagnosis of external warts is based on their clinical appearance. Multiple treatments exist, but few are highly effective unless applied repeatedly over weeks to months. Genital warts may resolve without treatment in immunocompetent patients but may persist and spread in patients with decreased cell-mediated immunity (eg, due to pregnancy or HIV infection).

In the US, an estimated 1.4 million people have genital warts at any given time. There are about 6 million new cases of genital HPV infection each year, and about 80% of women have been infected at least once by age 50. Most infections clear spontaneously within 1 to 2 yr, but some persist.

Etiology

There are > 70 known types of HPV. Some types cause common skin warts (see Viral Skin Diseases: Warts), but others infect primarily the skin and mucosa of the anogenital region. Important manifestations of anogenital HPV include

• Genital warts (condyloma acuminatum)
• Intraepithelial neoplasia and carcinoma of the cervix, anus, or penis
• Bladder and oral cancers
• Bowenoid papulosis

Condylomata acuminata are benign anogenital warts most often caused by HPV types 6 and 11. Low- and high-grade intraepithelial neoplasia and carcinoma may be caused by HPV types 16 and 18 and probably other types.

HPV is transmitted from lesions during skin-to-skin contact. The types that affect the anogenital region are usually transmitted sexually by penetrative vaginal or anal intercourse, but digital, oral, and nonpenetrative genital contact may be involved.

Genital warts are more common among immunocompromised patients. Growth rates vary, but pregnancy, immunosuppression, or maceration of the skin may accelerate the growth and spread of warts.

Symptoms and Signs

Warts appear after an incubation period of 1 to 6 mo. Visible anogenital warts are usually soft, moist, minute pink or gray polyps (raised lesions) that enlarge, may become pedunculated, have rough surfaces, and may occur in clusters. They are usually asymptomatic, but some patients have itching, burning, or discomfort.

In men, warts occur most commonly under the foreskin, on the coronal sulcus, within the urethral meatus, and on the penile shaft. They may occur around the anus and in the rectum, especially in homosexual men. In women, warts occur most commonly on the vulva, vaginal wall, cervix, and perineum; the urethra and anal region may be affected. HPV types 16 and 18 usually cause flat endocervical or anal warts that are difficult to see and diagnose clinically.

Genital Warts (Male)

Genital Warts (Female)

Diagnosis

• Clinical evaluation, sometimes including colposcopy, anoscopy, or both

Genital warts are usually diagnosed clinically. Their appearance usually differentiates them from condyloma lata of secondary syphilis, which are flat-topped. However, serologic tests for syphilis (STS) should be done initially and after 3 mo. Biopsies of atypical, bleeding, ulcerated, or persistent warts may be necessary to exclude carcinoma. Endocervical and anal warts can be visualized only by colposcopy and anoscopy. Applying a 3 to 5% solution of acetic acid for a few minutes before colposcopy causes warts to whiten and enhances visualization and detection of small warts. Nucleic acid amplification tests (NAAT) for HPV DNA confirm the diagnosis and allow typing of HPV, but their role in HPV management is not yet clear.

Treatment

• Manual removal (eg, by cryotherapy, electrocauterization, laser, or surgical excision)
• Topical treatment (eg, with antimitotics, caustics, or interferon inducers)

No treatment of anogenital warts is completely satisfactory, and relapses are frequent and require retreatment. In immunocompetent people, genital warts may resolve without treatment. In immunocompromised patients, warts may be less responsive to treatment.

Genital warts may be removed by cryotherapy, electrocauterization, laser, or surgical excision; a local or general anesthetic is used depending on the size and number to be removed. Removal with a resectoscope may be the most effective treatment; a general anesthetic is used.

Topical antimitotics (eg, podophyllotoxin, podophyllin, 5-fluorouracilSome Trade Names
ADRUCIL
Click for Drug Monograph
), caustics (eg, trichloroacetic acid), and interferon inducers (eg, imiquimodSome Trade Names
ALDARA
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) are widely used but usually require multiple applications over weeks to months and are frequently ineffective. Before topical treatments are applied, surrounding tissue should be protected with petroleum jelly. Patients should be warned that after treatment, the area may be painful.

Interferon alfa (eg, interferon alfa-2bSome Trade Names
ROFERON
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, interferon alfa-n3Some Trade Names
INTRON
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), intralesionally or IM, has cleared intractable lesions on the skin and genitals, but optimal administration and long-term effects are unclear. Also, in some patients with bowenoid papulosis of the genitals (caused by type 16 HPV), lesions initially disappeared after treatment with interferon alfa but reappeared as invasive cancers.

For intraurethral lesions, thiotepaSome Trade Names
No US trade name
Click for Drug Monograph
(an alkylating drug), instilled in the urethra, is effective. In men, 5-fluorouracilSome Trade Names
ADRUCIL
Click for Drug Monograph
applied bid to tid is highly effective for urethral lesions, but rarely, it causes swelling, leading to urethral obstruction. Endocervical lesions should not be treated until Papanicolaou (Pap) test results rule out other cervical abnormalities (eg, dysplasia, cancer) that may dictate additional treatment.

By removing the moist underside of the prepuce, circumcision may prevent recurrences in uncircumcised men.

Sex partners of women with endocervical warts and of patients with bowenoid papulosis should be counseled and screened regularly for HPV-related lesions. A similar approach can be used for HPV in the rectum.

Current sex partners of people with genital warts should be examined and, if infected, treated.

Prevention

A quadrivalent vaccine that protects against the 2 types of HPV (types 6 and 11) that cause > 90% of visible genital warts is available. This vaccine also protects against the 2 types of HPV (types 16 and 18) that cause most cervical cancers. The HPV vaccine has been recommended for girls and women aged 9 to 26 yr for prevention of initial infection. Three doses are given, preferably at age 11 to 12 yr. The vaccine should be administered before onset of sexual activity, but girls and women who are sexually active should still be vaccinated. The vaccine's role in preventing HPV in boys and men has not been established. A bivalent vaccine against HPV types 16 and 18 is awaiting approval.

Because of the location of these warts, condoms may not fully protect against infection.

Last full review/revision November 2008 by J. Allen McCutchan, MD, MSc

Content last modified November 2008