14
Alimentary Tract (Esophagus, Stomach, Small Intestine, colon, Rectum, Anus, Biliary Tract)
Duodenum
Normal Histology and cytology
Although the adult small intestine measures approximately
20 feet in length, only the proximal portion of the duodenum
is sampled, to any extent, for cytologic specimens. The sur-
face area of the duodenal mucosa is markedly expanded by
numerous villi, which by brushings are finger-like projections.
The majority of the mucosal surface is covered with tall colum-
nar absorptive epithelial cells characterized by a small basally
oriented oval nucleus with pale, fine chromatin and minute
nucleoli. The N/C ratio is very low, as the bulk of the cell is
made up of granular eosinophilic cytoplasm. The apical surface
of the absorptive cells is distinctive in that it stains much more
intensely; this is referred to as its striated border. Intermingled
among the absorptive cells are the mucus-producing goblet
cells. Small numbers of mature lymphocytes normally migrate
through the epithelium.
In brushings and transduodenal aspirates large flat sheets
of uniform epithelial cells are evident. A honeycomb pattern is
present in the flat monolayers. Three-dimensional aggregates, at
times with a villous configuration, may also be present. When
seen on end, the absorptive cells manifest a tall columnar
configuration, cyanophilic cytoplasm, a low N/C ratio, and an
accentuated luminal border. The clear barrel-like outline of the
goblet cells is evident.
infections
Cytom egalovirus
CMV is a common cytomorphologically recognizable infection
of the duodenum in patients who are immunocompromised.
This virus shows a proclivity to infect glandular cells as well
as stromal elements. The characteristic cellular inclusions may
be seen in surface epithelium, crypt lining cells, and fibroblast
endothelial cells in the superficial wall. Thus, in contrast to
the esophagus, the detection of this infection is not always
associated with an ulcer.
In cytologic samples, the virocytes resemble those described
earlier.67,127 They show prominent nucleomegaly and cytome-
galy, large basophilic inclusion bodies within the nucleus, a
broad halo separating the inclusion from the thickened nuclear
membrane, and occasional cytoplasmic inclusions. A major dif-
ference from specimens from the esophagus is that the virocytes
are much more numerous (Fig. 14.23). Furthermore, they may
be seen in cohesive aggregates of glandular epithelium, rather
than as isolated cells.
Helicobacter
The most common form of duodenitis is a nonspecific, variably
severe mucosal inflammatory process associated with concurrent
or prior peptic ulcers. Reactive or nonerosive duodenitis may
be associated with dyspepsia, but these gross and microscopic
changes may be found in patients who are asymptomatic. His-
tologically, the lamina propria and the glandular apparatus are
infiltrated by neutrophils, eosinophils, and mononuclear cells,
with an expansion of the lamina propria when the changes are
severe. In addition, gastric surface cell metaplasia may be seen in
biopsies. When
Helicobacter
is present, the organism is physically
(pseudopyloric) associated with these metaplastic elements. The
surface epithelium may also show regenerative changes.
Cytologic specimens resemble those obtained from patients
with Helicobacter-associated gastritis (Fig. 14.13). Smears con-
tain acute and chronic inflammatory cells and glandular colum-
nar cells manifesting the alterations of reparative atypia.
Giardia
Giardiasis is the most common intestinal pathogenic protozoan
in the Western world. Persons of all ages may be affected, but
disease is especially frequent in children. Often, the infection is
totally asymptomatic, with these individuals acting as carriers.
Other individuals may develop clinical disease, most frequently
diarrhea that varies from a very mild to a severe intractable
condition. Rarely, steatorrhea results. Individuals with late-onset
hypogammaglobulinemia may be more prone to develop severe
clinical manifestations.
Endoscopically, the duodenal mucosa may appear totally
unremarkable or show varying degrees of flattening. Diagnosis
is most often made by identification of cysts in stool specimens.
Less often, duodenal biopsy and aspiration are used. Duodenal
biopsies may appear totally unremarkable, with preservation of
normal architecture and cellular constituents. The only abnor-
mality may be the presence of trophozoites of
Giardia lamblia
in
close apposition to the mucosal surface. In patients with hypo-
gammaglobulinemia, the mucosa may be markedly altered by
diffuse nodular lymphoid hyperplasia, with enlarged lymphoid
follicles with prominent germinal centers, blunting of villi, and
markedly reduced numbers of plasma cells.
The trophozoites of
Giardia
may be identified in duode-
nal cytologic brushing specimens. The trophozoites measure
12 to 15 pm in maximum dimension and have a characteris-
tic pear-shaped configuration or, when seen on edge, a sickle
shape.121 Two "mirror image" nuclei are noted in the thick por-
tion of the organism opposite the tapering flagella. These nuclei
are usually not well visualized with the Papanicolaou stain.
When present in large numbers, the trophozoites may yield a
granular green background appearance. The organisms are best
visualized on DQ staining (Fig. 14.24).
Fig. 14.23 CMV duodenitis. Most of the glandular cells in this field have
enlarged nuclei, each with a prominent nuclear inclusion surrounded by
a broad halo and thick nuclear membrane. Multinucleation is not present
(Papanicolaou x HP).
395
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