Anal intraepithelial neoplasia: A review of diagnosis and management

Core tip: Anal intraepithelial neoplasia (AIN) is the precursor lesion to anal squamous cell carcinoma. AIN incidence is low in the general population, but rivals colon cancer in high risk groups, particularly those with human immunodeficiency virus infection and men who have sex with men. Thus, screening for AIN and early anal cancer and treatment of these lesions at expert centers should be considered in high risk populations. Screening is performed using anal cytology and high resolution anoscopy, and treatment consists of either topical or ablative therapies. Finally, human papillomavirus vaccination appears to reduce the rate of AIN and possibly anal cancer.