Anal Squamous Intraepithelial Lesion (ASIL) or Anal Dysplasia.
What is AIN?
AIN (Anal Intraepithelial Neoplasia) is characterised by the presence of abnormal cells that it is
believed that it may precede anal cancer.
Where does it occur?
AIN abnormal cells may occur in the anal canal (inside the back passage), in the peri-anal skin
(the skin around the back passage) or both.
What causes AIN?
AIN is thought to be caused by anal warts (Human Papilloma Virus) infection.
Who is at high risk for AIN?
• Those that engage in anal intercourse
• Patients that have undergone transplant surgery
• Women diagnosed with cervical cancer or Cervical Intraepithelial Neoplasia (CIA)
Why are they at high risk?
A combination of immunosuppression (decreased body's immune system and its ability to fight
infections or disease) and the presence of anal warts significantly increases the risk of AIN and
Immunosuppression is caused by HIV infection itself or by the medication given to patients with
a transplant in order to avoid its rejection.
URL: www.AINinfo.co.uk Email: [email protected] What are the symptoms of AIN?
Patients with AIN may not experience any obvious symptoms or they may experience locally the
How is AIN diagnosed?
• Health care providers are aware of patients at risk see above) and this is the first step of
diagnosis of AIN. Patients are then referred to specialist centres.
• Anal cytology smears (similar to the cervical PAP smear test) may reveal underlying AIN.
• The so called “High Resolution Anoscopy” is a special technique using an anoscope for visual
examination of the anal canal. A chemical (Acetic Acid) is administered in the back passage
• Conventional “Proctoscopy” is an alternative technique for visual examination of the anal
canal to identify intra-anal warts (warts inside the back passage) and other suspicious
changes of the lining of the back passage.
• Removal of the anal warts surgically and biopsies obtained from suspicious areas in and
outside the back passage in an examination under general anaesthetic is currently the most
definitive diagnostic test. Specimens are sent to specialist doctors that will identify the
presence of AIN under the microscope and grade it (see below).
• AIN is occasionally an incidental finding of specimens obtained from piles, skin tags and other
URL: www.AINinfo.co.uk Email: [email protected] Are there any different types of AIN?
• AIN Grade 1: is considered to show mild changes to abnormal cells
• AIN Grade 2: moderate changes to abnormal cells.
• AIN Grade 3: severe changes to abnormal cells.
• Low grade anal dysplasia (AIN 1 – 2)
AIN Grade 3 is a progressive, potentially precancerous condition that requires attention whether
the person is HIV positive or not. A small proportion of AIN Grade 3 tissue changes that are not
treated or removed may develop into anal cancer.
What is the treatment of AIN?
There is no definite therapy for AIN yet. This is because there is still a lot to be learned about
AIN and its association with anal cancer as well as the fact that there is no effective treatment
widely available. Regular follow up of patients with AIN may detect early anal cancer making the
Several treatments have been described in literature. These include:
• Imiquimod cream: This cream applied directly to affected areas works by stimulating the
immune system to release a number of chemicals called cytokines, which are important in
fighting viruses and destroying cancer cells. It is shown to be effective in other areas of the
body, however, there are few data available on its use in AIN.
• HPV Vaccine: This is still being investigated for the prevention of CIN and there are no
• Photodynamic Therapy (PDT): This is a treatment that uses laser light and a substance that
causes a chemical reaction that results in destruction of the abnormal cells (AIN affected
areas). The success of this treatment in skin tumours has prompted its use for AIN, however
there are still only a few studies available in literature.
URL: www.AINinfo.co.uk Email: [email protected]
• Surgery: There are different ways to treat surgical AIN Grade 3 affected areas. This would
involve the removal of the affected AIN area. There is strong evidence that HIV positive
patients have a high risk of recurrence and the need for many consequent operations with
several complications has made this approach unpopular.
Prevention is currently the best treatment. This can be achieved by safe sex in order to prevent
HIV infection, however, it has been shown that HPV can penetrate latex condoms.
I have AIN 3. What are the chances of developing anal cancer? Tell me more about anal cancer? URL: www.AINinfo.co.uk Email: [email protected] URL: www.AINinfo.co.uk Email: [email protected]
Servicio de Clínica Medica – Hospital Municipal de Agudos “Dr. Leónidas Lucero” Patología/Condición HEMORRAGIA DIGESTIVA ALTA (HDA) NO VARICOSA Autores López, Ana Clara; Uranga, Rolando Darío; Maruenda Maximiliano Martín Definición La HDA no varicosa se define como el sangrado del tracto digestivo desde el esfínter esofágico superior hasta el ángulo de Treitz que
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