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Anus and perianal area

Premalignant lesions


Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 15 April 2013, last major update April 2005
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.


● Also called anal intraepithelial neoplasia (AIN), anal canal intraepithelial neoplasia (ACIN), carcinoma in situ (if high grade)
● AIN/ACIN I-III (1-3) represents low grade/condyloma, intermediate grade and high grade/CIS lesions, respectively
● Occurs in perianal skin or anal canal in flat mucosa or with condyloma acuminatum
● May be incidental finding in hemorrhoid specimen; in these cases, excision is usually curative even for high grade AIN/ACIN (Hum Pathol 1991;22:528)
● Often multicentric
● HPV is commonly detected in these lesions (usually HPV 16, 18); presence does not appear to be associated with histologic features
● HIV patients often have high risk HPV types within low grade lesions (Arch Pathol Lab Med 1997;121:820)


● Cytology helpful for detection, Thin-Prep is better than smears (Mod Pathol 1995;8:270)

End of Anus and perianal area > Premalignant lesions > Dysplasia

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