Anal Intraepithelial Neoplasia (AIN)

What is anal intra-epithelial neoplasia?
Anal intra epithelial neoplasia AIN is a condition which affects the skin around the anus.  The severity of the condition is graded from I to III, with III being the most severe. AIN is important because some cases of AIN III can go on to develop into an anal cancer.

What causes anal intra-epithelial neoplasia?
Most AIN is triggered by the human papilloma virus (HPV). This is the same virus that causes anal warts. AIN is also related to changes in the vulva (Vulval Intra-epithelial Neoplasia, VIN) and cervix (Cervical Intra-epithelial Neoplasia, CIN) in women.
The human papilloma virus is the common link between all these conditions.
Other recognised risk factors include smoking and immunosuppression. Patients may be immunosuppressed because they are taking drugs to suppress their immune systems such as transplant patients. Other causes of immune suppression include HIV (Human Immunodeficiency Virus) infection.
Patients with AIN who are immunosuppressed are at greater risk of developing anal cancer.


What are the next steps?
If you think you have this condition or any of these symptoms
you will need to seek medical advice.
For more information or to make an appointment.
Contact birmingham bowel clinic on 0845 241 7762
or email
If you have private medical care or wish
to pay to see a consultant.
Take this factsheet along to your own
GP and request a referral to one
of our consultants
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