Anal Dysplasia

Anal dysplasia is changes in your body that could become anal cancer. Anal dysplasia isn’t cancer. Medical researchers believe variants of the human papillomavirus (HPV) cause nearly all cases of anal dysplasia. People can reduce their risk of developing anal dysplasia by being vaccinated against HPV and by reducing their risk of HPV infection.


What is anal dysplasia?

Anal dysplasia is a term healthcare providers use to describe changes in your body that could become cancer in your anus. Anal dysplasia isn’t cancer. It’s a sign you could develop anal cancer. In anal dysplasia, cells in your anus — the last section of your intestine — become abnormal. Over time, these abnormal cells could start multiplying, creating tumors. These tumors can spread to other areas of your body.

Medical researchers believe variants of the human papillomavirus (HPV) cause nearly all cases of anal dysplasia. People can reduce their risk of developing anal dysplasia by being vaccinated against HPV and by reducing their risk of HPV infection. Researchers have identified several other factors that increase the risk that someone will develop anal dysplasia, including having human immunodeficiency virus (HIV).

How does anal dysplasia affect my body?

Anal dysplasia starts in your mucosa, the moist inner lining of your anal canal. (Your anal canal extends from your anus to your rectum.) In anal dysplasia, healthy cells in your mucosa change into abnormal cells. These abnormal cells typically develop where your anal canal meets your rectum, but they can develop in the skin just outside your anus (perianal skin.)

Anal dysplasia doesn’t always cause symptoms. When it does, the symptoms may include things like having a very itchy anus or possibly feeling a lump or bump if you poke your finger into your anus. Some people with anal dysplasia notice warts in their anus. These warts aren’t cancer. They’re an HPV symptom.

Healthcare providers may refer to anal dysplasia as anal intraepithelial neoplasia (AIN) or as squamous intraepithelial lesions (SILs). Providers place AIN/SILs in two categories. They do that by examining cells under a microscope. AIN/SILs categories are:

  • Low-grade SIL (grade 1 AIN or low-grade dysplasia):The cells in low-grade SIL look like healthy cells. Low-grade SIL often goes away without treatment and isn’t likely to become cancer.
  • High-grade SIL (grade 2/grade AIN or high-grade dysplasia): The cells in high-grade SIL look abnormal. High-grade SIL is less likely to go away without treatment. In time, high-grade SIL could become anal cancer.
What are the chances of anal dysplasia turning into anal cancer?

Low-grade anal dysplasia (LSIL) doesn’t turn into anal cancer. A 2020 study estimated 3% to 14% of people with high-grade anal dysplasia (HSIL) develop anal cancer. The chance that anal dysplasia will become anal cancer varies based on people’s situations. For example, one study indicated about half of people with HIV and anal dysplasia developed anal cancer.

Is anal dysplasia common?

No, it’s not common. A 2018 review stated about 2 people in 100,000 have anal dysplasia.

Who does anal dysplasia affect?

Anal dysplasia affects people between ages 50 and 80. Nearly all people with anal dysplasia also have specific types of HPV.


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Symptoms and Causes

What are anal dysplasia symptoms?

Anal dysplasia often causes no symptoms. When symptoms are present, they may include:

  • Anal itching.
  • A feeling that there’s a lump or mass in your anus.
  • Pain.
  • Anal bleeding.

What causes anal dysplasia?

Medical researchers have identified several risk factors that increase the chance you’ll develop anal dysplasia. Risk factors include:

  • Having specific types of HPV.
  • Having a history of anal intercourse, even if you use condoms. That’s because HPV can spread in areas that condoms don’t cover.
  • Testing positive for HIV.
  • Smoking cigarettes.
  • Having a weak immune system from certain medications or autoimmune conditions.

Diagnosis and Tests

How do healthcare providers diagnose anal dysplasia?

Healthcare providers may use several tests to diagnose anal dysplasia. If you’re being evaluated for anal dysplasia, a provider may ask about your medical history, including if you have HIV or HPV. Possible tests include:

  • Digital rectal examination: A provider examines your anus for any lumps.
  • Anal Pap smear: This test is similar to Pap smears done to detect dysplasia or cancer in people’s cervixes. Providers do this test by inserting a cotton swab into your anus to collect cells. Medical pathologists examine the cells for signs of precancerous or cancerous changes.
  • Anoscopy: Providers use an anoscope — a small hollow tube with a bright light — to examine your anus. They insert the anoscope into your anal canal to check for abnormal cells. Sometimes, providers do a high-resolution anoscopy (HRA). In this test, providers spread certain substances in your anal canal that highlight any abnormal or precancerous areas.
  • Biopsy: If preliminary tests show signs of abnormal cells, providers may remove tissue from your anal canal. Medical pathologists examine cells to confirm a dysplasia or anal cancer diagnosis.
  • Computed tomography (CT) scan: If tests show signs of anal cancer, providers may use this test to see if the cancer has spread.

Management and Treatment

How do healthcare providers treat anal dysplasia?

Treatment varies based on the extent and kind of anal dysplasia you have. For example, if tests show you have low-grade dysplasia, your provider may simply monitor your situation to see if the dysplasia gets worse. (Remember, dysplasia sometimes appears and goes away without treatment.) If you have high-grade dysplasia, they may use one or more of the following treatments:

  • Chromoendoscopy: In this treatment, healthcare providers use an endoscope and stains that highlight abnormal tissue. An endoscope is a thin, flexible tube providers use to look at your gastrointestinal tract. As they examine your anus, your healthcare provider will destroy any abnormal cells. Destroying the cells eliminates the possibility that you’ll develop anal cancer.
  • Laser treatment: Providers remove the abnormal tissue with a laser.
  • Electrocautery (EC): Using the same instrument they used to do a biopsy, providers gently brush the affected area and remove abnormal cells.
  • TCA (trichloroacetic acid): Providers treat the affected area by touching it with an acid-soaked cotton pad.
  • Surgery: A surgeon removes the affected area.

What are the side effects of these treatments?

Each treatment has different side effects, from mild pain to mild bleeding. Your provider will select the treatment most likely to resolve your issue with the fewest side effects. They’ll explain the treatment options and what you can expect following treatment.



How can I reduce my risk of developing anal dysplasia?

The most effective way to avoid anal dysplasia is to protect yourself against the HPV types that cause the condition. Ways to reduce your HPV risk include:

  • Getting an HPV vaccine:HPV infections cause anal dysplasia. Being vaccinated against HPV reduces your risk of developing anal dysplasia.
  • Using a condom:HPV is a sexually transmitted disease (STD). People who participate in receptive anal sex, use sex toys or have multiple sex partners should take steps to protect themselves and their partners.
  • Have regular STD tests:Regular tests may let you know if you’ve been exposed to HPV.
  • Limit the number of sex partners:Having many sex partners increases your risk of HPV infection.
  • Stop smoking:Smoking increases your risk of developing anal dysplasia.

Should I be screened for anal dysplasia?

That depends on your situation. People who have an increased risk for anal dysplasia may benefit from regular screening. People at increased risk include:

  • People with HIV.
  • People who have anal sex on a regular basis.
  • People with a history of anal warts or precancerous cell growth in their anus.
  • People who’ve had other HPV-related cancers, including cervical cancer, vulvar cancer and vaginal cancer.
  • People with immune systems that have been weakened by certain autoimmune disorders and medication.

Outlook / Prognosis

What can I expect if I have anal dysplasia?

It’s important to remember anal dysplasia isn’t anal cancer. It’s also important to remember having anal dysplasia doesn’t mean you’ll develop cancer. If you have anal dysplasia, a healthcare provider will evaluate your situation, recommend treatment and explain what you can expect.

Living With

How do I take care of myself?

Having certain variants of HPV increases the chance you’ll develop anal dysplasia. If you have HPV, take steps to protect yourself and your sex partners:

  • Always use a condom.
  • Limit the number of people with whom you have sex.
  • Have regular tests for STDs.

If you don’t have HPV, take steps to avoid HPV infections by getting the HPV vaccine.

When should I seek care?

You should talk to a healthcare provider if you:

  • Have persistent anal itch.
  • Notice a lump in your anus.
  • Have pain in your anus.
  • Have anal bleeding.

What questions should I ask a healthcare provider?

If you’ve been diagnosed with anal dysplasia, you may want to ask the following questions:

  • What caused this condition?
  • Does having this condition mean I have HIV?
  • What is the dysplasia grade?
  • Will I develop anal cancer?
  • What treatment do you recommend?

A note from Cleveland Clinic

Anal dysplasia happens when you have changes in your anus that could become anal cancer. It’s important to remember anal dysplasia isn’t cancer and many times doesn’t become anal cancer. Anal dysplasia has some symptoms that may be embarrassing, like a persistent anal itch. And it’s commonly caused by human papillomavirus, a sexually transmitted disease that affects 1 in 4 adults in the U.S. But don’t let a potentially embarrassing symptom or cause keep you from talking to a healthcare provider.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 01/10/2023.

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