What Is Anal Dysplasia?
Anal dysplasia or anal neoplasia refers to precancerous cells in the anus. The anus is located at the end of the digestive tract and has specialized functions for bowel movements and continence.
The cells of the anus are susceptible to anal cancer, a squamous cell carcinoma. Dysplasia means that the cells are abnormal and can be diagnosed by biopsy or by Pap smear. Anal dysplasia is also known as AIN, LSIL and HSIL.
Is anal dysplasia cancer?
No, anal dysplasia is not cancer. Dysplasia can represent precancerous cells that have the potential over time to become cancerous. Some dysplasias regress on their own and some require surgical treatment to prevent progression to cancer.
What causes anal dysplasia?
The main contributing factor to the development of anal dysplasia and anal cancer is HPV infection (human papillomavirus). HPV is a very common virus that is typically spread through intimate skin-to-skin contact. Many people are unaware they have the infection because HPV often does not cause noticeable symptoms. In some cases, however, a persistent HPV infection can lead to atypical cellular changes in the lining of the anal canal. Certain strains of HPV can cause cancer in the anus, cervix, vagina, throat and penis.
Risk factors associated with anal dysplasia or anal cancer include:
- HIV disease
- Immunosuppression from certain medications, including biologic or steroid therapy for autoimmune disorders, transplant medication and some chemotherapy
- A history of genital warts
- A prior HPV-related disease such as dysplasia or cancer of the cervix, vulva, penis or throat.
- Smoking and other forms of tobacco use
- Men who have sex with other men
How are HPV and anal dysplasia connected?
HPV can infect cells in the anal canal, although the body’s immune system often clears the infection without causing long-term problems. Sometimes, however, HPV can persist in the body and lead to ongoing changes in the infected cells.
Certain HPV strains, such as HPV 16 and HPV 18, are considered high risk because they are more strongly linked to cancer. Persistent infection with high-risk HPV can lead to abnormal cell growth in the anal canal. Over time, these changes may develop into anal dysplasia.
What are low-grade and high-grade anal dysplasia?
Anal dysplasia, also known as anal intraepithelial neoplasia (AIN), may be classified as low-grade or high-grade based on how abnormal the cells appear under a microscope and how much of the anal lining is affected. Low-grade anal dysplasia generally involves milder cellular changes that may resolve on their own, remain stable, or, less commonly, progress.
High-grade anal dysplasia usually involves more significant cellular changes that may be considered precancerous anal lesions. Because these lesions are associated with a greater risk of progression, they may require closer monitoring and/or treatment by an appropriate specialist.
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Recognized for its scientific excellence, Moffitt is the only National Cancer Institute-designated Comprehensive Cancer Center based in Florida.
Does anal dysplasia cause symptoms?
Anal dysplasia often does not cause noticeable symptoms. Many people learn they have abnormal cells only after undergoing anal cancer screening or follow-up testing.
When symptoms do occur, they may overlap with those of other anal or rectal conditions.
Possible signs include anal itching, discomfort, bleeding, a lump or growth near the anus, unusual anal discharge or changes in bowel habits. Although these signs do not necessarily indicate anal dysplasia or anal cancer, they should be discussed with a health care provider.
How is anal dysplasia diagnosed?
Anal dysplasia may be detected through an anal cancer screening test, such as an anal Pap smear, which collects a small sample of cells from the anal canal for examination by a pathologist. If the results are abnormal, additional testing may be recommended.
A common follow-up test after an abnormal anal Pap smear is a high-resolution anoscopy. This procedure uses magnification to allow the physician to closely examine the anal canal and identify suspicious areas. If abnormal tissue is found, a biopsy and treatment may be performed.
How is anal dysplasia monitored or treated?
The monitoring or treatment plan for anal dysplasia can vary based on the grade of the dysplasia and the patient's overall health, symptoms, immune status and risk factors. In some cases, periodic anal Pap tests, high-resolution anoscopies or biopsies may be recommended to monitor for changes over time.
If active treatment is recommended, the goal is usually to remove or destroy the abnormal cells before they can progress. Options may include topical medications or an office-based procedure, such as electrocautery or another ablative therapy, performed by a specialist in anal dysplasia care.
What is high-resolution anoscopy?
High-resolution anoscopy or HRA is a specialized procedure where the surgeon examines the anus and cellular changes using a microscope. Abnormal areas can be identified and treated. High-resolution anoscopy has been shown to be the most effective way to prevent anal cancer in high-risk patients with anal dysplasia.
Moffitt Cancer Center is a leading center for HPV disease and anal dysplasia. Moffitt’s expert surgeons are nationally recognized as leaders and pioneers in HRA. Our surgeons are certified in this specialized procedure and participate in international research studies regarding HPV and anal dysplasia. Moffitt has advanced microscopes and technology to diagnose and treat anal dysplasia.
When should I talk with a specialist?
It is important to see a physician for symptoms such as anal bleeding, pain, itching, a lump or other unusual changes that do not go away. A physician may also recommend anal cancer screening for an individual who is at increased risk for HPV-related anal disease, has received an abnormal anal Pap smear, or has been diagnosed with anal dysplasia or high-grade anal lesions. High-risk patients should be screened annually.
Moffitt is a National Cancer Institute (NCI)-designated Comprehensive Cancer Center recognized for its research excellence and expertise in the evaluation and treatment of anal cancer, anal dysplasia and HPV disease. If anal cancer is suspected or diagnosed, the multispecialty team in our Gastrointestinal Oncology Program can help the patient understand their diagnosis and treatment options.
Medically reviewed by Julian Sanchez, MD, Gastrointestinal Oncology Program
If you would like to learn more about anal dysplasia or anal cancer, you can request an appointment with a specialist in the Gastrointestinal Oncology Program at Moffitt by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.