Page 167 - AIDSBK23C

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to invasive carcinomas. The relative risk for anal intraepithelial lesions is 60 in men and 7.8 in
women, compared with persons not infected with HIV.[711] Anorectal squamous cell dysplasia,
carcinoma, and condyloma acuminatum all have a higher incidence in young homosexual males
than in the general population, and this incidence is even greater (36%) in those homosexual
males who also have HIV infection. There is a strong association between the appearance of
these lesions and a history of receptive anal intercourse, particularly with multiple sexual
partners, but human papillomavirus (HPV) can be acquired without anal intercourse. The
concomitant presence of anal HPV is a risk for ASIL, and the risk for development of ASIL
increases when the CD4 lymphocyte count is lower, with smoking, and with increasing numbers
of sexual partners, though ASIL can occur even with CD4 counts which are less than
500/µL.[704,712,713,714]
There is a high prevalence of high-risk HPV types in the anus (78%), penis (36%), and
mouth (30%) in HIV-infected men, including both men who have sex with men as well as
heterosexual men.[715] The most common subtypes are HPV 16 (38%), 18 (19%), 45 (22%),
and 52 (19%). The HPV subtypes 16, 18, 31, 52, 59, and 68 are most likely to be associated with
high-grade ASIL.[716] The use of antiretroviral therapy (ART) increases survival in HIV
infected persons and appears to increase the risk for anal cancer, since HSIL does not appear to
regress with ART.[717]
Progression of ASIL to HSIL can occur in 17% of HIV-infected males, and this may
occur in less than a year. Risks for progression include coinfection with multiple HPV types,
specifically HPV 16 and a CD4 count <200/µL. Most persons with ASIL do not have regression
of the lesions while receiving antiretroviral therapy (ART). Thus, longer survival of persons
receiving ART may actually allow progression of ASIL to HSIL and invasive lesions.[714] In
such a setting, screening of HIV-infected persons, with risk factor of anal receptive intercourse,
by anal Pap smears can be useful.[718]
Carcinomas may occur in either the anal canal or the anal margin. Anal carcinomas are
usually squamous cell carcinomas, but some are adenocarcinomas. Those that occur at the anal
margin are less likely to be associated with HPV infection, but surgical excision alone is
typically curative. Surgery combined with chemotherapy and radiotherapy is employed in
treatment of carcinomas of the anal canal, but there is a high recurrence rate along with high
chemotherapy toxicity, and high mortality.[714]
Human papillomavirus (HPV) related anorectal condylomata are found in about 1 in 5
HIV-infected men. Other grossly apparent anal lesions can include hemorrhoids and fissures.
Receptive anal intercourse is the major risk factor for these lesions.[719]
Women with HIV infection are more likely to have anal HPV than non-HIV-infected
women, and they are more likely to have cytologic abnormalities of the anorectal mucosa. In
this setting, the risk for ASIL, HSIL, and invasive lesions is increased. In women, anal
intercourse is associated with risk for anorectal neoplasia.[720]
The transformation zone separating the rectal columnar mucosa from the anal
keratinizing squamous epithelium above the dentate line is the region where most intraepithelial
neoplasms arise. Histologic changes can include atypia, condyloma, and intraepithelial
neoplasia. More than two thirds of the squamous epithelial thickness is involved with HSIL, and
microinvasion may be present.[711]
Clinical features of anal intraepithelial neoplasia may include pain, pruritus, bleeding,
discharge, or tenesmus. The grossly visible anoscopic appearance may be normal. Anal
cytology may be useful for screening, because the positive predictive value for any anal