Page 470 - Problem-Based Feline Medicine

462 PART 7 SICK CAT WITH SPECIFIC SIGNS

● Sonographic abnormalities of the spleen include The benefit or detriment of chemotherapy in addition to
splenomegaly, irregular contour, mottled appear- surgery is not known. Prednisone alone or protocols
ance, and hyperechoic and hypoechoic nodules. used to treat lymphoma may be considered.
Lymph nodes may be hypoechoic. Intestinal masses
are hypoechoic and there is loss of normal wall lay-
Prognosis
ering. Effusion is anechoic.
The prognosis for splenic mast cell tumor is good,
Fine-needle biopsy of spleen, gastrointestinal mass
even with evidence of widespread dissemination.
or other organ based on clinical signs will often reveal
Median survival post-splenectomy is 12–19 months,
neoplastic mast cells. Surgical biopsy of intestinal
and peripheral mastocytosis declines.
masses may be required for diagnosis. Intraoperative
cytology is recommended, so that wide surgical exci- The prognosis for intestinal mast cell tumor is poor,
sion of the tumor(s) may follow. with most cats being euthanized soon after diagnosis or
● Abdominal fluid usually contains mast cells with treatment.
or without eosinophils. Occasionally no mast cells
are present.
RIGHT HEART FAILURE**
Fifty percent of cats with splenic mast cell tumor
will have mast cells in the peripheral blood on cyto- Classical signs
logic examination of direct smear or buffy coat smears.
● Dyspnea due to pleural effusion.
Other laboratory findings include hyperglobulinemia
and coagulation abnormalities.
Pathogenesis
Iron-deficiency anemia from chronic intestinal hem-
orrhage may occur with intestinal mast cell tumor. Cats with right heart failure usually develop pleural
effusion. Peritoneal effusion is a less common occur-
Eosinophilia may occur with visceral mast cell tumors.
rence.
● Peritoneal effusion has been observed with congen-
ital tricuspid valve dysplasia, patent ductus arte-
Differential diagnosis
riosus and intrapericardial heterotopic liver.
The main differential diagnosis for marked ● Peritoneal effusion has been observed with
splenomegaly is lymphoma, but it does not typically acquired pericardial effusion (which in-itself may
cause the massive splenomegaly seen in cats with mast be a sign of right heart failure), persistent atrial
cell tumor. standstill, traumatic tricuspid valvular insuffi-
ciency, tricuspid valvular endocarditis, myocarditis,
The main differential diagnoses for an intestinal mass
heartworm disease, severe chronic anemia, and
and abdominal distention are adenocarcinoma and
dilated, hypertrophic and restrictive cardiomy-
lymphoma. Chronic intussusceptions are rare, and
opathy. Of these various disorders, dilated car-
would not typically be associated with abdominal dis-
diomyopathy is most likely to cause peritoneal
tention or fluid.
effusion.
The presence of eosinophils in peritoneal fluid is not
Pulmonary edema may also be present due to left heart
specific for mast cell tumor, and has also been seen
failure.
with lymphoma, septic peritonitis and pneumotho-
rax. However, the presence of mast cells is highly spe-
cific for visceral mast cell tumor. Clinical signs
Peritoneal effusion is usually accompanied by pleu-
ral effusion. Pleural effusion ± pulmonary edema will
Treatment
cause dyspnea.
Splenectomy or excision with 5–10 cm margins of ● Most peritoneal effusion due to right heart failure
intestinal masses. causes undetected to minimal abdominal distention.