Clinical Manual for Management of the HIV-Infected ... - myCME.com

Anal Dysplasia
Background
Anal cancer is a squamous cell cancer associated with
human papilloma virus (HPV), the same virus that is
associated with cervical cancer (see chapter Cervical
Dysplasia). In the United States, the current incidence of
anal cancer in the general population is approximately
1:100,000 per year, and rising. The incidence of anal
cancer is significantly higher in HIV-infected women
and men than in the general population. Rates are also
higher in men who have sex with men (MSM), whether
HIV infected or uninfected. Before the HIV epidemic,
the anal cancer incidence in an MSM population was
35:100,000. Current rates in an HIV-infected MSM
population are as high as 70-80:100,000. Thus, the
incidence of anal cancer in this population is greater
than the incidence of cervical cancer in women before
the introduction of cervical cytology screening.
The cervical canal and anal canal share a common
embryologic origin: Both have a squamocolumnar
transition zone and are prone to infection with
genitotropic HPV, a sexually transmitted virus. HPV
infection, in combination with other cofactors, may
stimulate dysplastic changes in the cervix or anus that
may develop through precursor stages (squamous
intraepithelial lesions [SIL]) into squamous cell cancer.
A small but growing body of literature suggests a high
prevalence of anal HPV infection and dysplasia in
HIV-infected individuals. Some studies have shown
that, in HIV-infected individuals, anal HPV infection is
present in 93% of MSM and 76% of women, and anal
dysplasia (any grade) is present in 56% of MSM and
26% of women. Receptive anal intercourse (RAI) may
increase the likelihood of anal HPV infection, but is
not a prerequisite for anal HPV or dysplasia. In a study
of HIV-positive heterosexual men with no history of
RAI, anal HPV infection was found in 46% and anal
dysplasia in 32%. Patients with lower CD4 cell counts
appear to be at higher risk of developing anal dysplasia.
It is not clear whether effective antiretroviral therapy
(ART) and immune reconstitution offer protection
against dysplasia.
Prevention of HPV infection is difficult. Latex or plastic
barrier may be partially effective through bodily contact
outside the area covered by the barriers. Vaccines against
certain strains of HPV may be available soon, though
Section 6—Disease-Specific Treatment | 6–1
their efficacy in preventing anal dysplasia (as opposed
to cervical dysplasia), and their efficacy in HIV-infected
individuals, is unknown.
The field of anal dysplasia and anal cancer is a relatively
new area of scientific investigation, and many questions
about the disorder and its medical management remain
unanswered. Because of the similarities between
cervical and anal dysplasia, researchers postulate that
many of the paradigms of managing cervical cytologic
abnormalities may be translated to the anal canal. No
national or international guidelines have been developed
for anal cancer screening or the management of anal
dysplasia. Further, many centers lack the resources
for anal dysplasia screening and treatment. In areas
with adequate diagnostic and treatment resources,
some specialists recommend screening all HIVinfected
individuals for anal dysplasia; and if indicated,
intervening to prevent the development of anal cancer.
Further investigation is needed to define appropriate
screening intervals, diagnostic approaches, indications
for therapy, and modalities of treatment.
S: Subjective
Patients with anal dysplasia are usually asymptomatic
and the condition cannot be identified without
screening tests. Exophytic anal condylomata may
cause itching, discomfort, or bleeding, but are usually
associated with low-risk phenotypes of HPV and lowgrade
dysplasia. Anal cancer may cause nonspecific
symptoms such as pain, bleeding, and the development
of a mass lesion.
Risk factors for anal dysplasia are not well understood,
but include the following:
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Receptive anal intercourse (RAI)
HPV infection
Genital warts (or history of genital warts)
HIV infection
CD4 count