A CLINICO.PATHOLOGICAL STUDY OF ANAL FISTULAE

.a"nal Fbtula
Review of Lllerature
d- Endoscopic exflmination
The definitive diagnosis of CMV gastrointestinal disease depends on
invasive procedues and biopsies. Upper (Wilcox et al, 1990) and lower
(Rene et al, 1988) gastrointestinal endoscopic examinations of CMV
disease usually appears as a mucosal erosion or ulceration. Full
colonoscopic examination may identify more patients with CMV colitis
than does flexible sigmoido scopic examination (Dieterich and Rahmin,
ree.l).
*- Histopathologic Analysis
.t characteristicytopathic effect: a large 25 to 35 pm cell
cantaining a basophilic inffanuclEar inclusion, which is sometimes
surrounded by a clear halo ("owl's eye" effect) and is frequently associated
Muly with clusters of intracytoplasmic inclusions (see Figure l0)
studies have confirmed the specificity of cytomegalic cells for diagnosing
f"JIvlV.antigen because they are always associated with CMV antigan or
CMV DNA (Eyre- Brook et al, 1986), or both, as shown by special staining
techniques. However, in some proved cases of gastronitestinal CMV
disease, cytomegalicells may be rare and difficult to detect (Myerson et
al, 1984), requiring great time and effort by the pathologist (Culpepper-
Ir4organ et al, 1987). Success in finding these cells is a function of the
number of biopsy specimens examined and the diligence of the pathologist
(Goodgamet al, 1993). This lack of sensitivity is a disadvantage of
routine histopathologic examination.
e- Culture of Mucosal Biopsy $pecimens
Culture of endoscopic biopsy speciments adds expense that may not
be justified by an improvement in diagnostic yield when compared with
routine histopathologic analysis coupled with a vigorousearch for
cytomegalicells.
f- Immunochemicfll Staining of Histologic Specimens
lmmunoperoxidase or immunofluorescence staining for CMV
antigens using rnonoclonal antibodies (Culpepper-Morgan et al, 1987) and
in-situ DNA hybridization using a biotinJabeled probe, whereas antigen
staining indicates viral replication, DNA staining ocflrs with latent viral
infection. Two studies (Francis et al, 1989) reported that the
inrrnunoperoxidase stain was positive when routine histologic analysis
failed to show cytomegalicells. In a study of 80 symptomatic AIDS
patients who had gastrointestinal mucosal biopsies, l3 of 80 biopsies
(16.3%) were positive for CMV using in-situ DNA hybridizationl. Tested
in these same l3 biopsy specimens, the immunoperoxidase stain (7 of 13
positive) and Histopathologic stains (5 of l3) positive were less sensitive,
g- Polymerase Chain Reaction
In this small pilot study in AIDS patients, PCR had greater
sensitivity for detectin gastrointestinal CMV disease than culture and
immunoperoxidase stain. However, PCR is a technique with many
technical pitfalls and is not standardized for CMV diagnosis.
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