Anal Dysplasia: The Precancerous Cell Changes Linked to HPV — and What Treatment Prevents Cancer
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026
TL;DR
Anal dysplasia is a set of abnormal cell changes in the anus that could develop into anal cancer — but it is not cancer itself. Medical researchers believe variants of the human papillomavirus (HPV) cause nearly all cases. It most often affects people aged 50 to 80 and occurs in roughly 2 in 100,000 people. Low-grade dysplasia often resolves without treatment and does not turn into cancer, while an estimated 3% to 14% of people with high-grade dysplasia go on to develop anal cancer. Effective treatments remove or destroy the abnormal cells, and HPV vaccination plus safer-sex practices significantly reduce risk.
Quick Answer
What it is: Anal dysplasia refers to abnormal cell changes in the anus that could become anal cancer — it is not cancer itself.
Main cause: Variants of HPV are believed to cause nearly all cases; nearly all people with anal dysplasia carry specific HPV types.
Cancer risk: Low-grade dysplasia (LSIL) does not turn into anal cancer; a 2020 study estimated 3% to 14% of people with high-grade dysplasia (HSIL) develop anal cancer.
Prevention: HPV vaccination and reducing HPV exposure (condoms, fewer partners, STD testing, not smoking) are the most effective protective steps.
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 is 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 and 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 the condition by being vaccinated against HPV and by reducing their risk of HPV infection. Researchers have identified several other risk factors, including testing positive for HIV.
| Key Fact | Detail | | --- | --- | | Definition | Abnormal cell changes in the anus that could become cancer — but not cancer itself | | Primary cause | HPV variants — believed to cause nearly all cases | | Prevalence | About 2 in 100,000 people | | Most common age range | 50 to 80 years old | | Cancer progression | Only high-grade dysplasia carries meaningful cancer risk |
Where Does Anal Dysplasia Develop?
Anal dysplasia starts in the mucosa, the moist inner lining of the anal canal. Your anal canal extends from your anus to your rectum. Healthy cells in the mucosa change into abnormal cells.
These abnormal cells typically develop where the anal canal meets the rectum, but they can also develop in the skin just outside the anus (the perianal skin).
Anal dysplasia doesn't always cause symptoms. When it does, symptoms may include a very itchy anus or possibly feeling a lump or bump. Some people notice warts in their anus. These warts aren't cancer — they are an HPV symptom.
What Are the Two Grades of Anal Dysplasia?
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 by examining cells under a microscope.
| Feature | Low-Grade SIL (Grade 1 AIN) | High-Grade SIL (Grade 2/3 AIN) | | --- | --- | --- | | Also called | Low-grade dysplasia / LSIL | High-grade dysplasia / HSIL | | Cell appearance | Cells look like healthy cells | Cells look abnormal | | Without treatment | Often goes away on its own | Less likely to go away | | Cancer risk | Not likely to become cancer | Could become anal cancer over time | | Typical management | Monitoring | Treatment to remove/destroy abnormal cells |
What Are the Chances of Anal Dysplasia Turning into Anal Cancer?
The cancer risk depends heavily on the grade. Low-grade anal dysplasia (LSIL) does not turn into anal cancer. A 2020 study estimated that 3% to 14% of people with high-grade anal dysplasia (HSIL) develop anal cancer.
The chance that anal dysplasia becomes anal cancer varies based on a person's situation. For example, one study indicated that about half of people with HIV and anal dysplasia developed anal cancer.
How Common Is Anal Dysplasia?
No, it is not common. A 2018 review stated that about 2 people in 100,000 have anal dysplasia. It primarily affects people between ages 50 and 80, and nearly all people with anal dysplasia also have specific types of HPV.
What Are the Symptoms of Anal Dysplasia?
Anal dysplasia often causes no symptoms. When symptoms are present, they may include anal itching, a feeling that there is a lump or mass in the anus, pain, or anal bleeding.
| Symptom | Notes | | --- | --- | | No symptoms | Most common presentation | | Anal itching | Persistent itch; can feel embarrassing to mention | | Feeling of a lump or mass | May be felt when touching the area | | Anal warts | An HPV symptom — the warts themselves are not cancer | | Pain | In or around the anus | | Anal bleeding | Bleeding from the rectal area |
What Causes Anal Dysplasia?
Medical researchers have identified several risk factors that increase the chance of developing anal dysplasia. The central cause is infection with specific types of HPV.
| Risk Factor | Why It Increases Risk | | --- | --- | | Specific types of HPV | Believed to cause nearly all cases | | History of anal intercourse | HPV can spread in areas that condoms don't cover, even with condom use | | Testing positive for HIV | Substantially raises progression risk | | Smoking cigarettes | Increases the risk of developing anal dysplasia | | Weakened immune system | From certain medications or autoimmune conditions |
How Is Anal Dysplasia Diagnosed?
Healthcare providers may use several tests to diagnose anal dysplasia. Your provider may first ask about your medical history, including whether you have HIV or HPV.
| Test | How It Works | | --- | --- | | Digital rectal examination | A provider examines the anus for any lumps | | Anal Pap smear | A cotton swab collects cells, similar to cervical Pap smears; pathologists examine them for precancerous or cancerous changes | | Anoscopy | A small hollow tube with a bright light examines the anal canal; high-resolution anoscopy (HRA) uses substances that highlight abnormal or precancerous areas | | Biopsy | Tissue is removed from the anal canal; pathologists confirm a dysplasia or anal cancer diagnosis | | CT scan | If tests show signs of anal cancer, this checks whether the cancer has spread |
How Is Anal Dysplasia Treated?
Treatment varies based on the extent and kind of anal dysplasia you have. If tests show low-grade dysplasia, your provider may simply monitor the situation to see if the dysplasia gets worse — dysplasia sometimes appears and goes away without treatment.
If you have high-grade dysplasia, providers may use one or more of the following treatments:
| Treatment | How It Works | | --- | --- | | Chromoendoscopy | An endoscope with stains highlights abnormal tissue; the provider destroys any abnormal cells, eliminating the possibility of developing anal cancer | | Laser treatment | Abnormal tissue is removed with a laser | | Electrocautery (EC) | Using the biopsy instrument, providers gently brush the affected area and remove abnormal cells | | TCA (trichloroacetic acid) | The affected area is treated with an acid-soaked cotton pad | | Surgery | A surgeon removes the affected area |
Each treatment has different side effects, ranging from mild pain to mild bleeding. Your provider will select the treatment most likely to resolve your issue with the fewest side effects and explain what you can expect afterward.
What Can I Expect if I Have Anal Dysplasia?
It is important to remember that anal dysplasia isn't anal cancer. Having anal dysplasia doesn't mean you will develop cancer. If you have anal dysplasia, a healthcare provider will evaluate your situation, recommend treatment, and explain what you can expect.
How Can I Reduce My Risk of Anal Dysplasia?
The most effective way to avoid anal dysplasia is to protect yourself against the HPV types that cause the condition. Note that HPV is a common sexually transmitted infection that affects about 1 in 4 adults in the U.S.
| Prevention Step | How It Protects | | --- | --- | | HPV vaccination | Reduces your risk of developing anal dysplasia by protecting against the causative HPV types | | Using a condom | HPV is an STD; people who have receptive anal sex, use sex toys, or have multiple partners should protect themselves and their partners | | Regular STD tests | May reveal prior HPV exposure | | Limiting the number of sex partners | Having many partners increases HPV infection risk | | Stopping smoking | Smoking increases the risk of developing anal dysplasia |
Should I Be Screened for Anal Dysplasia?
That depends on your situation. People at increased risk may benefit from regular screening:
| Higher-Risk Group | Reason | | --- | --- | | People with HIV | Elevated cancer-progression risk | | People who have anal sex regularly | Higher HPV exposure | | People with a history of anal warts or precancerous cell growth | Recurrence risk | | People with other HPV-related cancers | Including cervical, vulvar, and vaginal cancer | | People with weakened immune systems | From autoimmune disorders or certain medications |
How Do I Take Care of Myself?
Having certain variants of HPV increases the chance you will 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, and have regular STD tests.
If you don't have HPV, take steps to avoid infection by getting the HPV vaccine.
When Should I Seek Care?
Talk to a healthcare provider if you have persistent anal itch, notice a lump in your anus, experience pain in your anus, or have anal bleeding. It is worth emphasizing that embarrassing symptoms or causes — like an itchy anus or an HPV connection — should never keep you from talking to a provider.
Questions to Ask Your Healthcare Provider
If you have been diagnosed with anal dysplasia, consider asking: 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?
Conclusion
Anal dysplasia sits at the intersection of two highly common realities: HPV, which affects roughly 1 in 4 U.S. adults, and a set of precancerous cell changes that sound far scarier than they often turn out to be. The single most important fact is this: anal dysplasia is not cancer, and it does not automatically become cancer.
Low-grade dysplasia frequently resolves without treatment and does not progress to cancer. High-grade dysplasia carries a real but quantified risk — an estimated 3% to 14% progression per a 2020 study — and it is treatable. Chromoendoscopy, laser treatment, electrocautery, TCA application, and surgery all remove or destroy the abnormal cells, and chromoendoscopy in particular eliminates the possibility of developing anal cancer from the treated area.
The prevention toolkit is equally actionable: HPV vaccination, condom use, regular STD testing, limiting partners, and quitting smoking. For people in higher-risk groups — those living with HIV, those with prior anal warts or HPV-related cancers — regular screening can catch dysplasia before it progresses.
CTA: If you notice persistent anal itch, a lump, pain, or bleeding, see a healthcare provider and ask about anal dysplasia screening. And if you or your child hasn't received the HPV vaccine, ask your provider whether it's right for you — it is the most effective single step toward preventing anal dysplasia.
FAQ
What is anal dysplasia?
Anal dysplasia refers to abnormal cell changes in the anus that could become anal cancer. It is not cancer itself — it is a warning sign that anal cancer could develop. The abnormal cells typically start in the mucosa, the moist inner lining of the anal canal, usually where the anal canal meets the rectum.
What causes anal dysplasia?
Medical researchers believe variants of the human papillomavirus (HPV) cause nearly all cases. Nearly all people with anal dysplasia have specific types of HPV. Other risk factors include a history of anal intercourse, testing positive for HIV, smoking, and a weakened immune system from certain medications or autoimmune conditions.
Is anal dysplasia cancer?
No. Anal dysplasia is a set of precancerous cell changes. Having it does not mean you will develop cancer. Low-grade dysplasia often goes away without treatment and is not likely to become cancer.
What is the difference between low-grade and high-grade anal dysplasia?
Low-grade dysplasia (LSIL, grade 1 AIN) cells look like healthy cells, often resolve without treatment, and do not turn into anal cancer. High-grade dysplasia (HSIL, grade 2/3 AIN) cells look abnormal, are less likely to resolve on their own, and could become anal cancer over time — though a 2020 study estimated only 3% to 14% of people with HSIL develop anal cancer.
What are the symptoms of anal dysplasia?
Anal dysplasia often causes no symptoms at all. When present, symptoms may include a persistent itchy anus, a feeling of a lump or mass in the anus, pain, anal bleeding, or anal warts (which are an HPV symptom, not cancer).
How is anal dysplasia diagnosed?
Providers take a medical history and may perform a digital rectal exam, an anal Pap smear (a swab collects cells for pathologist review), anoscopy or high-resolution anoscopy (HRA), a biopsy, and — if cancer is suspected — a CT scan to check for spread.
How is anal dysplasia treated?
Low-grade dysplasia is often simply monitored, since it may resolve on its own. High-grade dysplasia is treated by removing or destroying abnormal cells through chromoendoscopy, laser treatment, electrocautery, trichloroacetic acid (TCA) application, or surgery. Side effects are usually mild, ranging from mild pain to mild bleeding.
How can I reduce my risk of anal dysplasia?
The most effective steps target HPV: get vaccinated against HPV, use condoms, have regular STD tests, limit the number of sex partners, and stop smoking. People at higher risk — including those with HIV, a history of anal warts, or other HPV-related cancers — may benefit from regular screening.
References
American Society of Clinical Oncology. Anal Cancer: Introduction. https://www.cancer.net/cancer-types/anal-cancer/introduction
American Society of Colon and Rectal Surgeons. Anal Warts and Anal Dysplasia Expanded Information. https://www.fascrs.org/patients/disease-condition/anal-warts-and-anal-dysplasia-expanded-information
CATIE. HPV, anal dysplasia and anal cancer. https://www.catie.ca/en/fact-sheets/cancers/hpv-anal-dysplasia-and-anal-cancer
Centers for Disease Control and Prevention. STD Facts — Human Papilloma Virus. https://www.cdc.gov/std/hpv/stdfact-hpv.htm
HPV and Anal Cancer Foundation. Living with Anal Cancer/Anal Precancer. https://www.analcancerfoundation.org/living-with-anal-cancer/anal-pre-cancer/
Palefsky JM, Lee JY, Jay N, Goldstone SE, Darragh TM, Dunlevy HA, et al. Treatment of Anal High-Grade Squamous Intraepithelial Lesions to Prevent Anal Cancer. N Engl J Med. 2022 Jun 16;386(24):2273-2282. https://pubmed.ncbi.nlm.nih.gov/35704479/
Disclaimer: This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for guidance specific to your situation.
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