Anal dysplasia means abnormal, precancerous cells in the lining of the anal canal, almost always caused by high-risk HPV; left unchecked, high-grade dysplasia can progress to anal cancer. HPV causes more than 90% of anal cancers NCI. Screening the people at highest risk can catch and treat lesions before cancer develops.
within 2 years
prevents, doesn't treat
| Item | Value |
|---|---|
| Clears on its own | 9 in 10 — within 2 years |
| Wart types | 6 & 11 |
| Cancer types | 16, 18 + |
| Vaccine | Gardasil 9 — prevents, doesn't treat |
The essentials: what anal dysplasia and cancer actually are
Anal dysplasia is the abnormal growth of squamous cells around the anal opening and inside the anal canal. Clinicians grade it by how abnormal the cells look. Low-grade changes often clear on their own, while high-grade squamous intraepithelial lesions (HSIL) are the ones that can turn into invasive cancer over years. Dysplasia isn't cancer; it's the warning stage before it, much like cervical precancer is to cervical cancer.
The driver is human papillomavirus, the most common STI CDC. The same high-risk types that cause cervical cancer — chiefly 16 and 18 — cause anal cancer. The low-risk types that cause genital warts (6 and 11) do not cause cancer. People routinely blur these two problems, but they're different infections with different consequences.
Most HPV infections cause no trouble: about nine out of ten clear on their own within two years without any health problems. Cancer happens in the minority of cases where a high-risk infection persists for years and slowly damages the cells. HPV reaches well beyond the cervix, causing cancers of the cervix, vulva, vagina, penis, anus, and the back of the throat. You can read more about hpv leading to other kinds of cancers, but vaccine does help to reduce cervical cancer, and about the broader picture of seven viruses causing cancer, including hpv & epstein-barr virus.
Higher risk falls on people living with HIV, men who have sex with men, anyone who is immunocompromised (including transplant recipients on anti-rejection drugs), and people with a history of HPV-related disease elsewhere, such as cervical or vulvar precancer. Receptive anal contact raises exposure, but HPV can reach the anal area without it.
Symptoms: what anal dysplasia and early cancer feel like
Anal dysplasia usually causes no symptoms, which is why screening exists for high-risk groups. High-risk HPV is typically silent, producing no visible bump and no discomfort. By the time symptoms appear, the process has often moved past dysplasia toward invasive disease.
Symptoms that should prompt a clinic visit include:
- Bleeding from the anus or blood on toilet paper, which people often dismiss as hemorrhoids.
- A lump or mass at or just inside the anal opening that doesn't go away.
- Persistent anal itching, pain, or a feeling of fullness or pressure.
- A change in bowel habits or the caliber (width) of stool, or unusual discharge.
- Swollen lymph nodes in the groin, which can signal that a cancer has begun to spread.
None of these is specific to cancer — hemorrhoids, fissures, and warts cause the same complaints. That overlap matters, because bleeding written off as piles can delay a diagnosis. Genital and anal warts usually show up as a small bump or group of bumps; they're caused by low-risk HPV and don't become cancer, but their presence confirms HPV exposure and is a reason to discuss screening.
Testing: how anal dysplasia is found
The guidance here is in flux. An anal Pap (anal cytology) swabs cells from the anal canal to look for abnormal changes, much like a cervical Pap. Abnormal cytology is followed by high-resolution anoscopy (HRA), a magnified look at the anal lining with a colposcope-like scope, where a clinician applies acetic acid and iodine to highlight suspicious areas and takes a biopsy to confirm the grade of dysplasia. A digital rectal exam is also part of a thorough evaluation.
On routine screening, CDC's 2021 guidance found the data insufficient to recommend routine anal cytology, even for men who have sex with men or people with HIV CDC STI Guidelines. That position predates the 2022 ANCHOR trial, which showed that treating anal high-grade lesions reduced anal cancer in people with HIV. Since then, some specialty groups such as IDSA/HIVMA suggest periodic anal Pap for high-risk groups in places where HRA referral is available. It is not a blanket CDC recommendation, so practice varies by clinic and by access to a trained anoscopist.
There's no general 'HPV test' that screens you for anal or oropharyngeal risk. HPV tests are not recommended to screen men, adolescents, or women under age 30, and they aren't used to diagnose warts. So HPV usually won't appear on a standard STD panel — see does hpv show up on an std test? for the full explanation. For other infections and timing, here's when to test after exposure, and you can get tested for the panel that fits your situation.
Treatment: managing dysplasia versus treating warts
Two things get confused here. Wart treatments and dysplasia treatments are not the same, and neither cures the virus itself.
High-grade anal dysplasia is managed with targeted, lesion-directed procedures done under high-resolution anoscopy — typically ablation of the abnormal area (for example with electrocautery or infrared coagulation) or office-applied agents to destroy the precancerous tissue. The aim is to remove HSIL before it can progress. Because HPV persists, new lesions can appear, so people in screening programs are followed over time with repeat anoscopy.
Invasive anal cancer is treated by oncology specialists, usually with a combination of chemotherapy and radiation (chemoradiation) and surgery in selected cases. That care is outside the scope of this page and belongs with a cancer team.
Anogenital warts, a separate problem, are treated to clear the visible bumps, not the virus. Options fall into two camps:
| Approach | Examples | What to expect |
|---|---|---|
| Patient-applied (at home) | Imiquimod 3.75% or 5% cream; podofilox 0.5% solution or gel; sinecatechins 15% ointment | Applied over weeks; sinecatechins are not recommended for immunocompromised or HIV-positive patients |
| Provider-administered (in clinic) | Cryotherapy with liquid nitrogen or cryoprobe; TCA or BCA 80%–90% solution; surgical removal by excision, curettage, laser, or electrosurgery | Done in visits; freezing is quick but may need repeating |
No single wart treatment is clearly best, and because the therapy clears the bumps but not the underlying virus, warts can recur after they're gone. Treating warts does nothing to manage cancer precursors, which are handled separately through screening and anoscopy.
Prevention: the vaccine, screening, and condoms
The HPV vaccine is the strongest tool, and it prevents cancer rather than treating it. Given at the recommended ages, it can prevent more than 90% of HPV-caused cancers, and Gardasil 9 is about 98% effective against the precancers caused by HPV 16 and 18 ACS. Gardasil 9 — the only HPV vaccine distributed in the US since 2016 — protects against nine types: 6, 11, 16, 18, 31, 33, 45, 52, and 58. Types 16 and 18 alone cause about 66% of cervical cancers, the five added high-risk types about another 15%, and types 6 and 11 cause more than 90% of genital warts CDC Pink Book.
The vaccine protects against future infection. It won't clear an infection or warts you already have, and it won't reverse existing dysplasia. Even fully vaccinated people still need cervical screening, because no vaccine covers every cancer-causing type.
Condoms give partial protection only, since HPV can infect skin a condom doesn't cover. For people with a cervix, cervical screening remains a backstop: current guidance starts at 25 with a primary HPV test every 5 years (preferred) over a yearly Pap, because most HPV clears within two years and HPV testing catches more real precancer with fewer visits ACS. There's no equally established population-wide anal screening program yet, so knowing your risk category matters.
When to see a clinician
Don't self-diagnose anal bleeding as hemorrhoids. See a clinician if you have ongoing anal bleeding, a lump that doesn't resolve, persistent itching or pain, a change in stool, or a groin lump. If you're living with HIV, are immunocompromised, are a man who has sex with men, or have had HPV-related precancer elsewhere, ask your provider directly whether anal screening makes sense for you and whether high-resolution anoscopy is available locally. Access drives whether screening is even an option.