The prevalence of AIN has remained high among HIV-positive MSM after the introduction of HAART. Our data indicate that HAART is not associated with a reduced prevalence of AIN and support measures to prevent anal cancer among HIV-positive MSM whether or not they are using HAART.

HIV infection, lower CD4 levels and human papillomavirus infection were associated with high rates of incident HSIL among homosexual men. However, high rates were found at all CD4 levels among HIV-positive men and among HIV-negative men.

The B19 parvovirus is a remediable cause of severe chronic anemia in HIV-infected patients. Recognition of and therapy for parvovirus in this population will avoid erythrocyte transfusion and should prevent transmission of the virus to other persons, including immunosuppressed persons and women of child-bearing age.

The colposcopic appearance of different grades of anal squamous intraepithelial lesions was similar to those described for the cervix. Incorporation of colposcopy into assessment of anal disease could aid in distinguishing anal LSIL from HSIL.

Anal cancer may be preceded by anal squamous intraepithelial lesions (ASIL), but the natural history of ASIL is poorly understood. In this report, we characterize the 2-year incidence and progression of low-grade SIL (LSIL) and high-grade SIL (HSIL) in a cohort study in 346 HIV-positive and 262 HIV-negative homosexual or bisexual men. Subjects were studied at defined intervals using anal cytology, anoscopy with biopsy of visible lesions, human papillomavirus (HPV) testing, HIV serostatus, CD4 level, and data on medical history and lifestyle. The incidence of HSIL within 2 years was 20% in HIV-positive men and 8% in HIV-negative men who were normal at baseline. In total, 62% of HIV-positive and 36% of HIV-negative men with LSIL at baseline progressed to HSIL. The relative risk (RR) for anal disease progression in HIV-positive men was 2.4 (95% confidence interval [CI], 1.8-3.2) when compared with HIV-negative men. The RR increased to 3.1 (95% CI, 2.3-4.1) in HIV-positive men with CD4 counts <200/mm3. Infection with multiple HPV types was a risk factor for anal disease progression in both HIV-positive (RR = 2.0; 95% CI, 1.0-4.1) and HIV-negative (RR = 5.1; 95% CI, 2.3-11) men. The incidence of anal HSIL and progression of LSIL to HSIL within 2 years of follow-up is high in HIV-positive homosexual or bisexual men and to a lesser extent, in HIV-negative men. Men with the above risk factors may be at increased risk of developing anal cancer.

Surgical intervention directed by high-resolution anoscopy is safe and eliminates high-grade squamous intraepithelial lesions in human immunodeficiency virus-negative patients. The high persistence or recurrence rate in human immunodeficiency virus-positive patients suggests that multiple staged procedures and continued surveillance may be necessary.

Sensitivity and specificity of anal cytology and human papillomavirus testing are different in HIV-positive and HIV-negative MSM for detecting high-grade anal neoplasia when patients have high-resolution anoscopy-guided biopsy of lesions. The optimum use of human papillomavirus testing has yet to be defined. High-resolution anoscopy is an effective tool for diagnosing high-grade anal neoplasia.

The incidence of anal cancer is elevated in human immunodeficiency virus (HIV)-infected men-who-have-sex-with-men (MSM) compared to the general population. Anal high-grade squamous intraepithelial lesions (HSIL) are common in HIV-infected MSM and the presumed precursors to anal squamous cell cancer; however, direct progression of HSIL to anal cancer has not been previously demonstrated. The medical records were reviewed of 138 HIV-infected MSM followed up at the University of California, San Francisco, who developed anal canal or perianal squamous cancer between 1997 and 2011. Men were followed up regularly with digital anorectal examination (DARE), high-resolution anoscopy (HRA) and HRA-guided biopsy. Although treatment for HSIL and follow-up were recommended, not all were treated and some were lost to follow-up. Prevalent cancer was found in 66 men. Seventy-two HIVinfected MSM developed anal cancer while under observation. In 27 men, anal cancer developed at a previously biopsied site of HSIL. An additional 45 men were not analyzed in this analysis due to inadequate documentation of HSIL in relation to cancer location. Of the 27 men with documented progression to cancer at the site of biopsy-proven HSIL, 20 men progressed from prevalent HSIL identified when first examined and seven men from incident HSIL. Prevalent HSIL progressed to cancer over an average of 57 months compared to 64 months for incident HSIL. Most men were asymptomatic, and cancers were detected by DARE. Anal HSIL has clear potential to progress to anal cancer in HIV-infected MSM. Early diagnosis is facilitated by careful follow-up. Carefully controlled studies evaluating efficacy of screening for and treatment of HSIL to prevent anal cancer are needed.The incidence of anal cancer continues to increase annually in the general population. 1 Prior to the availability of effective antiretroviral therapy (ART), the estimated incidence of anal cancer among human immunodeficiency virus (HIV)-infected men-who-have-sex-with-men (MSM) was nearly 60-fold higher than men in the general population. 2 Although the incidence of other viral-associated malignancies has decreased in HIV-infected MSM as a result of ART, anal cancer incidence has increased, and its incidence in HIV-infected MSM is now estimated to be 80 times higher than men in the general