anal intraepithelial neoplasia

(redirected from Anal Squamous Intraepithelial Lesions)
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anal intraepithelial neoplasia

A carcinoma in situ of the anorectal mucosa that is embryologically, histologically, and pathologically analogous to cervical intraepithelial neoplasia, which is linked to HPV infection and divided into low-grade (LG-AIN) and high-grade (HG-AIN) tumours, the latter of which is associated with aggressive squamous cell carcinoma.

Risk factors
Anal HPV infections, receptive anal intercourse, HIV infection and decreased CD4-+ve T cells.
 
HPV types
6/11, 31/33/35 and 16/18.

anal intraepithelial neoplasia

Abbreviation: AIN
A precancerous change in the squamous cells of the anus that may eventually develop into anorectal cancer. It is similar to cervical intraepithelial neoplasia in that it is a premalignant lesion that arises in squamous cells, is found primarily in sexually active people, and is associated with human papillomavirus and HIV.
Synonym: anal dysplasia; anal squamous intraepithelial lesion
See also: neoplasia