trophozoites have a characteristic pear shape
(Diff Quik x HP),
In the past cryptosporidiosis was considered a rare infection
of the human GI tract. Recently, infections have become more
recognized in both immunocompetent and immunosuppressed
patients, especially those with AIDS.162,163 The organism infects
the human small and large intestines. As with
site is transmitted by a fecal-oral route. Severity of disease var-
ies among individuals, with most patients manifesting diarrhea
and fever. Symptoms tend to be chronic and more severe in
those who are immunosuppressed.
The diagnosis is usually made by the identification of oocysts in
stool specimens or, less often, by mucosal biopsy. Histologically,
the organism presents as a small spherical structure attached to
the luminal surfaces of columnar epithelial cells. Some authors
have found that the number of organisms present in the biopsy
correlates with the severity of the clinical picture.162,163
In brushing specimens,
2 to 4 pm in diameter, have round to pyramidal configurations,
and appear basophilic.127 With the Diff-Quik stain, a stippled
appearance may be evident. Characteristically, the organisms
are in intimate contact with the luminal surfaces of otherwise
normal glandular cells (Fig. 14.25).
Classic tuberculosis and atypical mycobacterium may involve
the small intestine. Although uncommon in the United States,
in India ileocecal tuberculosis remains a significant problem.
Endoscopic biopsies and brushings are usually nondiagnos-
tic. Transmucosal FNA cytology has been more useful in the
diagnosis of mycobacterial infections.127 EUS-guided FNA of
regional lymph nodes is especially useful in this regard with suf-
ficient material for culture obtained. The smears typically show
necrotic debris, and inflammatory cells including lymphocytes
Atypical mycobacterial infection can commonly involve
the duodenum in AIDS patients. Diagnostic negative images
of mycobacterium avium (MAI) can be seen in air-dried DQ
or Wright-Stained smears.164 PAP stained smears show numer-
ous foamy and striated macrophages (pseudo-Gaucher cells)
(Fig. 14.26A). The diagnosis can be confirmed with special stains
such as Ziehl-Neelsen, AFB, PAS, or FITE (Fig. 14.26B).
organisms are in intimate
contact with the luminal surface of benign glandular cells (Diff Quik x HP),
Although benign peptic ulcers are far more common in the
duodenum than in the stomach, they are sampled for histology
and cytology far less frequently than their gastric counterparts.
The clinical presentation and histopathology essentially mirror
those in the stomach. Cytologic brushings are also basically the
same. They include flat sheets of normal glandular cells, as well
as those showing reparative atypia, neutrophils, and granular
may also be evident.
The relative frequencies of different malignant neoplasms pri-
mary in the small intestine differ remarkably from those in
the esophagus, stomach, and colon. If the entire length of the
small intestine is considered, malignant lymphomas, carcinoid
tumors, and adenocarcinomas occur in relatively equal num-
bers; stomal tumors are less frequent. In the duodenum, the
portion generally accessible to the endoscope, adenocarcinoma
is the most frequent malignancy. These neoplasms may present
clinically with jaundice, anemia, or symptoms of obstruction.
Within the duodenum, they occur most often in the immediate
vicinity of the papillae of Vater, where they usually present as
an exophytic mass. Ulcerating carcinomas are not common in
the duodenum, which is, hence, the major reason for the lack
of endoscopic biopsies and brushings of duodenal peptic ulcers.
More distally in the small intestine, these neoplasms often have
a napkin ring growth appearance, resulting in clinical obstruc-
tion. Histologically, small bowel adenocarcinomas show varying
degrees of differentiation, often have a papillary configuration,
and may be associated with residual adenoma. The overall prog-
nosis may be good if the tumor is small and discovered early,
generally as a result of the signs of jaundice. Otherwise, the out-
look is dismal.
Cytologically, these neoplasms basically resemble adeno-
carcinomas of the intestinal type in the stomach and Barrett's-
associated adenocarcinoma. Thus, these smears are generally
cellular with individually dispersed malignant cells as well as
cohesive aggregates, which vary from small spheres to large
branching papillary structures. Each cell possesses a single large
hyperchromatic and frequently elongated nucleus with obvious
nucleoli. Cytoplasm may contain distinct mucin vacuoles.