Anal intraepithelial neoplasia

Abstract

Anal intraepithelial neoplasia (AIN) is a well−recognized precursor of anal squamous cell carcinoma, and its incidence is reaching almost epidemic proportions in high−risk groups, particularly men who have sex with men (MSM), those infected with the human immunodeficiency virus (HIV), or immunosuppressed organ recipients. There is a clear aetiological association between AIN and human papillomavirus (HPV), but the natural history of AIN is unclear, although it is assumed that it resembles that of cervical intraepithelial neoplasia. Therefore, high risk individuals, and those healthcare professionals involved in their care should be made aware that the development of perineal warts or an intra−anal lump needs prompt referral for histological assessment. Non−surgical treatment of high−grade AIN and local excision of discrete lesions seems logical, as extensive prophylactic surgical treatments carry high morbidity, especially in immunocompromised patients, and the early removal of pre−malignant lesions, even if temporary, may impede progression to invasive cancer. Early detection of disease progression is essential to such a management strategy; as yet there is no standard surveillance protocol, but a reasonable approach is suggested.