Anal
diseases
Warts
These
are usually sexually transmitted, although anoreceptive intercourse is
probably not necessary for the development of anal canal warts (Fig. 9.3). The treatment of these warts
requires local scissor excision or destruction by some other local method, for
example diathermy or laser. Less extensive wart infection can be controlled by
application of podophyllin. The wart virus (human papilloma virus) is able to
incorporate in the human genome and some types promote cancer development. In
the presence of reduced immune surveillance, this can result in early neoplastic
change within the anal epithelium which is termed anal intraepithelial neoplasia
(AIN). The risk of progression of this intraepithelial neoplasia to invasive
anal malignancy is small, although a precise figure is unknown. The finding of
AIN in HIV disease is probably of little clinical significance since progression
to invasive malignancy is unlikely within the prognosis of the HIV disease. The
objective of anal wart treatment in these patients should be to control the
local discomfort or leakage associated with the warts. AIN may also occur in the
absence of warts (Fig. 9.4), although these patients are probably infected with
human papilloma virus.
Perianal
sepsis
The usual varieties of anal fistula can develop in HIV-positive
patients. The combination of local anal trauma resulting from anoreceptive sex
with reduced immunity probably results in an increased risk of perianal sepsis.
Perineal healing is reduced in patients with advanced HIV disease associated
with a low CD4+ lymphocyte count. In those patients who do not have a CD4+ count
of less than 100, conventional management of perianal sepsis is appropriate.
For patients with severe reduction in CD4+ count who are likely to have AIDS, a more conservative approach to control sepsis, for example, with the use of a seton, is probably more appropriate. It was initially believed that perianal sepsis was more complex in the HIV than in the non-HIV patient population. However, subsequent experience does not suggest that HIV-positive patients are more likely to have difficult or complicated high fistulas
Anorectal
ulceration
Ulcers may occur in any part of the anal canal (Fig. 9.5)
or
lower rectum, and are usually associated with AIDS. In some cases they can be
shown to be due to herpes simplex virus infection, but in other cases no
organism has been demonstrated, although infection remains the most likely
cause. Treatment for herpes simplex virus with acyclovir should be tried first.
Occasionally, excision of the ulcerated area with a gentle anal stretch can be
helpful. In some cases it is not possible to achieve healing of the ulcer.
Anal
neoplasia
The probability of an HIV-positive patient with anal symptoms having
anal neoplasia is much higher than in the nonHIV population. The commonest
anal neoplasms are squamous carcinoma of the anal canal (Fig.
9.6), Kaposi’s
sarcoma involving the anal canal, and perirectal or perianal non-Hodgkin’s
lymphoma. Lymphoma can produce a tense painful swelling in the ischiorectal
fossa which is easily mistaken for perianal sepsis. Thus needle aspiration is
helpful before incision and drainage of suspected ischiorectal abscesses in the
HIV-positive patient since this may avoid a breach in the skin overlying the
lymphoma with subsequent risk of ulceration. The majority of patients with anal
neoplasia has advanced HIV disease.
Homosexuals who undergo repeated anorectal intercourse weaken the
internal anal sphincter. The association of a weakened internal anal sphincter
with some degree of infective proctitis (see below) can produce minor faecal
incontinence.