Interventions for anal canal intraepithelial neoplasia.

Anal canal intraepithelial neoplasia (AIN) is a pre-malignant condition of the anal canal transitional epithelium that is associated with human papillomavirus (HPV) infection. The incidence and prevalence of AIN and anal cancer are increasing rapidly in HIV-positive men who have sex with men (MSM). Other groups like HIV-negative MSM, immunosuppressed patients and people affected by other HPV diseases like genital warts and cervical intraepithelial neoplasia (CIN) may also develop AIN. The condition is complicated by its multicentric and multifocal nature and high rates of relapse and morbidity. Targeted excisions using ablative treatments such as cautery, infrared coagulation (IRC) and cryotherapy have been used as first-line therapeutic strategies, and there are many other options. There is no consensus about the optimal management of AIN.