Anogenital dysplasia is a condition where cells in the genital or anal areas change from their normal form, creating patches of abnormal tissue that could potentially develop into cancer over time. While these cell changes are not yet cancer, understanding them and monitoring their progression is important for preventing more serious health problems down the road.

What Happens in Anogenital Dysplasia

When someone develops anogenital dysplasia, cells in specific areas of their body begin to look and behave differently than normal, healthy cells. The term dysplasia means abnormal growth or development. In this case, the abnormal cells appear in tissues of the genital or anal regions. These areas include the cervix, vagina, vulva, penis, scrotum, and the anal canal or the skin surrounding it.^[1]

The changed cells are not cancerous, and in many cases, anogenital dysplasia goes away on its own without any treatment. However, because these abnormal cells could be precancerous—meaning they have the potential to turn into cancer over time—doctors recommend monitoring the condition closely.^[1]

Most adults are exposed to human papillomavirus (HPV) at some point in their lives. HPV is a virus transmitted through skin-to-skin contact, and many cases of anogenital dysplasia and related genital conditions are linked to HPV infection. People with HPV often don’t realize they have the virus unless they develop a wart or receive an abnormal Pap smear result along with a positive HPV test.^[1]

How Common Is Anogenital Dysplasia

Looking at anal dysplasia specifically, which is one form of anogenital dysplasia, this condition is not very common. Studies suggest that about 2 people in 100,000 have anal dysplasia, making it a relatively rare diagnosis in the general population.^[3]

Most people affected by anal dysplasia are between the ages of 50 and 80. Nearly everyone who develops anal dysplasia also has specific types of HPV in their system.^[3]

Vaginal dysplasia, another type of anogenital dysplasia, is less common than cervical or vulvar dysplasia. It most commonly occurs in women in their 40s through 60s. Most cases of vaginal dysplasia are discovered during routine cervical cancer screening.^[18]

What Causes Anogenital Dysplasia

The primary cause behind most cases of anogenital dysplasia is infection with certain types of human papillomavirus. HPV is extremely common—the Centers for Disease Control and Prevention estimates that 85% of people will get an HPV infection at some point in their lives. HPV can infect the anus, perianal area, the mouth and upper airway, the cervix in women, and even the skin.^[5]

HPV infection at different body sites can be acquired through sexual contact or through skin-to-skin contact. However, having HPV doesn’t always lead to dysplasia. Some types of HPV are more likely to cause warts, some are more likely to cause dysplasia, and some are unlikely to cause any disease at all.^[5]

Medical researchers believe that variants of HPV cause nearly all cases of anal dysplasia. For other types of anogenital dysplasia, such as cervical or vaginal dysplasia, the same virus plays a central role in changing normal cells into abnormal ones.^[3]

Who Is at Higher Risk

Having one or more risk factors does not guarantee someone will develop anogenital dysplasia. Some people with no identifiable risk factors still develop this condition, while others with multiple risk factors never do. That said, certain groups of people face elevated risk.^[1]

People who have contracted HPV in their genital or anal area are at increased risk for developing anogenital dysplasia. Those who receive a Pap smear showing abnormal results are also in a higher-risk category. Having a weakened immune system—whether from human immunodeficiency virus (HIV), other autoimmune conditions, or medications that suppress the immune system—raises the likelihood of developing dysplasia. Such medications might be taken after an organ transplant or for conditions like rheumatoid arthritis.^[1]

A personal history of anogenital warts increases risk, as does a history of anal cancer, cervical cancer, vaginal cancer, or vulvar cancer. Other lifestyle and behavioral factors contribute as well. Having sexual intercourse without barrier methods such as condoms increases risk, as does having multiple sexual partners. Smoking cigarettes is another significant risk factor.^[1]

Certain groups are at particularly high risk for developing anal dysplasia specifically. Men who have sex with men face substantially elevated risk. Transgender women are also at higher risk. Women with a history of cervical, vaginal, or vulvar dysplasia or cancer have increased likelihood of developing anal dysplasia. People living with HIV, patients who have undergone solid organ transplants, and those on chronic immunosuppression or steroid medications all face higher risk.^[7]

People with weakened immune systems, including those receiving immune-suppressing medications and those with HIV infection, are more likely to acquire HPV infection and to develop disease related to HPV. These individuals require monitoring and testing for anal dysplasia to prevent or identify the development of anal cancer.^[5]

What Are the Symptoms

Most people with anogenital dysplasia experience no symptoms at all. The condition often exists silently in the body, discovered only through screening tests or examinations for other reasons. This lack of obvious signs makes regular screening important for people in high-risk groups.^[1]

When symptoms do appear, they can affect the anus or genital areas in various ways. People may notice abnormal discharge or bleeding that wasn’t present before. Itching in the affected area is another possible symptom. Some individuals feel a lump or small growth when they touch the area, or they experience persistent pain lasting longer than three to four weeks.^[1]

For anal dysplasia specifically, when symptoms are present, they may include anal itching, a feeling that there’s a lump or mass in the anus, pain, or anal bleeding. Some people with anal dysplasia notice warts in their anus, though these warts aren’t cancer—they’re an HPV symptom.^[3]

It’s worth noting that these symptoms can appear similar to symptoms of other common conditions, such as hemorrhoids or infections. Sometimes symptoms don’t appear until dysplasia has advanced to cancer, which underscores the importance of screening even when feeling well.^[8]

How to Prevent Anogenital Dysplasia

The most effective way to prevent anogenital dysplasia is to avoid getting high-risk HPV in the first place. Since HPV causes most cases of anogenital dysplasia, preventing HPV infection offers the best protection.^[10]

The most powerful tool against HPV is Gardasil, a vaccine that’s been available since 2006. The vaccine is recommended for everyone before the onset of sexual activity, ideally given to young people before they’re exposed to the virus. If you’re age 26 or younger, you can get the series of HPV shots, which protects against the types of HPV that can cause dysplasia. If you’re between ages 27 and 45 and haven’t been vaccinated for HPV, talk with your doctor about whether the vaccine is right for you.^[10]

Using latex condoms every time you have anal or genital sexual contact helps prevent HPV infection, though it’s unclear exactly how well they stop HPV transmission and the development of dysplasia. Condoms work best when used from the start to the end of sexual contact, covering the entire encounter. However, HPV can spread in areas that condoms don’t cover, so they offer incomplete protection.^[10]

Limiting your number of sexual partners reduces your risk of getting sexually transmitted infections, including HPV. Sexual activity with one partner who has sex only with you can help lower risk. If you have HPV, tell any sexual partners, because even if you don’t have symptoms, you can still pass HPV to others.^[10]

Stopping cigarette smoking is another prevention strategy. Smoking increases the risk of developing dysplasia and reduces the body’s ability to fight HPV infection. For people at elevated risk—such as those with HIV or weakened immune systems—regular screening tests allow for early detection and treatment before dysplasia progresses.^[3]

How Anogenital Dysplasia Changes the Body

To understand how anogenital dysplasia affects the body, it helps to know what happens to cells during this condition. In anal dysplasia, the changes begin in the mucosa, which is the moist inner lining of the anal canal. The anal canal extends from the anus to the rectum. In this condition, healthy cells in the mucosa transform into abnormal cells.^[3]

These abnormal cells typically develop where the anal canal meets the rectum, though they can also develop in the skin just outside the anus, called the perianal skin. Over time, if left untreated, these abnormal cells could start multiplying and creating tumors. In worst cases, these tumors can spread to other areas of the body, which is when dysplasia has progressed to cancer.^[3]

Healthcare providers classify anal dysplasia—also called anal intraepithelial neoplasia (AIN) or squamous intraepithelial lesions (SILs)—into categories based on how the cells look under a microscope. Low-grade SIL, also called grade 1 AIN or low-grade dysplasia, consists of cells that still look fairly similar to healthy cells. This type often goes away without treatment and isn’t likely to become cancer.^[3]

High-grade SIL, also called grade 2 or grade 3 AIN or high-grade dysplasia, consists of cells that look clearly abnormal when examined under a microscope. High-grade SIL is less likely to go away without treatment, and over time, it could become anal cancer if not addressed. A 2020 study estimated that 3% to 14% of people with high-grade anal dysplasia develop anal cancer. However, these odds vary considerably based on individual circumstances—for example, one study indicated about half of people with both HIV and anal dysplasia developed anal cancer.^[3]

For vaginal dysplasia, the precancerous condition starts in the skin inside the vagina. The cells undergo abnormal changes, and if left untreated, vaginal dysplasia can progress to vaginal cancer. It’s classified as low grade or high grade based on how severe the abnormality appears. Low-grade vaginal dysplasia often goes away without treatment, while high-grade dysplasia, considered precancerous, requires treatment to prevent abnormal cells from progressing to cancer.^[18]

The connection between HPV and these cellular changes involves the virus interfering with normal cell regulation. When HPV infects cells in the anogenital area, it can cause them to grow and divide abnormally, creating patches of dysplastic tissue. In people with healthy immune systems, the body often clears the infection before significant changes occur. But in those with weakened immunity, the virus persists, giving it more time to cause lasting cellular changes.^[5]