Anal squamous intraepithelial lesions: an update and proposed management algorithm.

The term anal squamous intraepithelial lesion (ASIL) is used to describe premalignant change of anal squamous cells that precede the development of squamous cell carcinoma. Pathophysiology is driven by the human papilloma virus (HPV), and progression and regression of ASIL being well described, with 12% of high-grade lesions progressing to invasive cancer within 5 years. Vaccination against HPV is effective for primary prevention. Management consists of identification and treatment of high-grade lesions to prevent progression to squamous cell carcinoma. Management of established ASIL aims to avoid the progression to invasive cancer and maintain fecal continence. A combination of surveillance, excision, ablative, or topical therapies is used to achieve this. The aim of the present study was to review the contemporary evidence about ASIL and to suggest a management algorithm.