Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Three The Abd omen 319
Because the normal stomach makes frequent mixing or propulsive motions, the stomach
should have different shapes on the multiple views taken during the GI series. If the
shape of the stomach fails to change, it indicates either gastric atony, which will be associated
with gastric dilation, or infiltration of the gastric wall, which will usually not have
marked gastric distention (Fig. 3-83). This radiographic appearance has been referred to as
a leather bottle stomach, because the shape of the stomach may be reminiscent of a leather
wineskin. Although all infiltrative lesions must be considered, the most likely diagnosis is
lymphosarcoma. Other differential diagnoses would include eosinophilic gastritis, gastric
adenocarcinoma, gastric fibrosis, mycotic lesions, or various less frequently seen neoplasms.
Gastric Wall Thickening. The normal gastric wall is smooth and uniform and is a few
millimeters thick when the stomach is fully distended. It may be appear much thicker if the
stomach is not distended. The gastric wall thickness may be somewhat difficult to perceive
in animals that do not have adequate body fat to allow identification of the serosal surface
of the stomach. In these instances, thickening may be suggested if there is an unusual
decrease in the size of the stomach lumen or if the stomach does not distend uniformly
when filled with air. Although gastric wall thickening is frequently due to gastric neoplasia,
granulomatous diseases or other infiltrative disease should also be considered in the diagnosis.
The types of gastric neoplasia include adenocarcinoma, lymphosarcoma, and
leiomyosarcoma. Although these lesions may resemble each other, the diagnosis frequently
can be suggested based on the pattern of change and clinical information. Adenocarcinoma
of the stomach usually appears as a regional thickening of the gastric wall.
Adenocarcinomas rarely have masses that protrude or extrude from the gastric wall. There
is a tendency to develop ulcers within the thickened gastric wall (Fig. 3-84). An important
factor to note when evaluating the lesion for possible treatment by gastrectomy is that the
tumor usually extends in the subserosa well beyond the area that is recognizable radiographically.
Lymphosarcoma usually appears as a more focal mass than adenocarcinoma,
or as a very diffuse lesion with only minimal to moderate wall thickening but with a lack
of motility (Fig. 3-85). Leiomyosarcoma tends to be a mass that extends out from the gastric
wall and has limited effect on the gastric lumen. Leiomyosarcoma may also appear as
a distinct mass within the stomach lumen. An infection that should be considered in cases
with gastric wall thickening is phycomycosis, or zygomycosis. 329 The lesion is most often
Fig. 3-83 A 7-year-old female
Siamese cat with vomiting for 2
weeks. Survey radiographs revealed
no abnormalities. The ventrodorsal
view of the GI series revealed a
slightly narrowed distal body and
pylorus of the stomach. There are no
indications of any gastric constriction
due to peristaltic or mixing
motions, nor were any indications
seen on other views. There is an
intraluminal mass in the proximal
duodenum (open black arrow) that
partially obstructs the lumen. The
gastric findings are indicative of an
infiltrative process. The duodenal
mass could be either a foreign body
or neoplasm. Differential diagnoses
of the stomach lesion include lymphoma,
adenocarcinoma, diffuse
granuloma, or chronic inflammatory
disease. Diagnosis: Diffuse lymphoma
of the stomach and focal
lymphoma of the duodenum.