Anal intraepithelial neoplasia

Br J Surg. 2005 Mar;92(3):277-90. doi: 10.1002/bjs.4967.


Background: Anal intraepithelial neoplasia (AIN) is believed to be a precursor of anal squamous cell cancer and its incidence is rising in high-risk groups, particularly those infected with the human immunodeficiency virus (HIV). The natural history of AIN is unclear and management strategies are lacking.

Methods: This review is based on a literature search (Medline and PubMed) with manual cross-referencing of all articles related to AIN.

Results and conclusions: The aetiology of AIN is intricately linked with human papilloma viruses. The pathological processes involved in the progression of AIN are becoming clearer but the natural history, particularly the rate of progression to invasive cancer, remains unknown. There is no standard management for AIN and this is mainly due to difficulties in both diagnosis and treatment. A variety of treatment options have been tried with varying success. Surgery is associated with significant recurrence, particularly in HIV-positive patients. Non surgical approaches with imiquimod, photodynamic therapy and vaccination are appealing, and further work is required. Long-term follow-up of these patients is essential until the natural history of AIN becomes clearer.

Publication types

  • Review

MeSH terms

  • Anal Canal / pathology*
  • Anus Neoplasms* / etiology
  • Anus Neoplasms* / pathology
  • Anus Neoplasms* / surgery
  • Carcinoma in Situ* / etiology
  • Carcinoma in Situ* / pathology
  • Carcinoma in Situ* / surgery
  • Carcinoma, Squamous Cell* / etiology
  • Carcinoma, Squamous Cell* / pathology
  • Carcinoma, Squamous Cell* / surgery
  • Female
  • HIV Infections / complications
  • Humans
  • Immune Tolerance
  • Male
  • Papillomavirus Infections / complications
  • Precancerous Conditions / etiology
  • Precancerous Conditions / pathology
  • Precancerous Conditions / surgery
  • Risk Factors
  • Tumor Virus Infections / complications