Anal intraepithelial neoplasia and anal cancer in dermatological practice.

Anal intraepithelial neoplasia is considered to be a precursor lesion of invasive anal cancer. It is now increasingly recognized in high-risk groups, such as men who have sex with men and HIV-infected patients. Human papillomaviruses are considered to be an important aetiological agent in both anal intraepithelial neoplasia and anal cancer. Dermatologists are likely to encounter these conditions among the differential diagnoses to be considered in high-risk patients presenting with perianal and anal lesions. Anal cancer rates are also increasing among the HIV-infected and HIV-non-infected population. The successful treatment of anal intraepithelial neoplasia may reduce the risk of subsequent development of anal cancer. However, current therapies for anal intraepithelial neoplasia may be associated with treatment-related morbidity and are not well validated. It is currently not proven that they reduce the likelihood of the development of anal cancer. Nevertheless, screening for anal intraepithelial neoplasia is being advocated for high-risk groups and may become standard dermatological care for these patients. In view of recent developments in the understanding of this condition, this article reviews the current understanding of anal intraepithelial neoplasia and its treatment from a dermatological perspective.