Anal Intraepithelial Neoplasia (AIN)
Another study of immunocompetent women found AIN in 70% of women with CIN. 4% of the women had HGAIN.
High grade AIN (HGAIN) is thought to be a true precursor to invasive anal cancer and is a real source of concern.
Risk factors of AIN in immunocompetent women include vaginal or vulva precancers, anal intercourse, unprotected anal intercourse and a history of genital herpes.
The risk factors for HGAIN among HIV-uninfected MSM include having any anal HPV infection and infection with an increasing number of HPV types.
The prevalence of AIN cancer is highest amongst HIV-infected MSM followed by HIV-uninfected MSM.
Anal intraepithelial neoplasia (AIN) shows many similarities under the microscope to atypical precursor changes of cervical cancer.
The analysis of immunocompetent women with precursors of cancer of the cervix, vulva or vagina demonstrated that 12% had biopsy-documented AIN, 8% of women had HGAIN.
AIN is found in only 6% of renal transplant recipient patient’s using anal cytology. It is noteworthy that this may be an underestimate of the prevalence of the disease because of the limited sensitivity of the cytology methodology for detection of AIN.
The only population based support to date, a post-HAART study in San Francisco demonstrated the prevalence of any grade of AIN was 57% in HIV-infected MSM and the prevalence of HGAIN was 43%.
Most of the studies to date on AIN have been done on MSM.
The prevalence of any grade AIN was 35% and the prevalence of HGAIN was 25% in HIV-uninfected MSM.