Page 1367 - Clinical Small Animal Internal Medicine

145 Liver and Biliary Tract Tumors 1305

discomfort, polyuria, polydipsia, diarrhea, seizures, is most common with HCC or bile duct carcinoma
VetBooks.ir weakness, ataxia, dyspnea, hematochezia or melena may whereas a ratio greater than 1 is more likely with a neu­
roendocrine or mesenchymal tumor.
be observed. If neurologic symptoms do occur in an
Other biochemical abnormalities commonly seen
affected patient, they may be caused by secondary
hepatic encephalopathy or paraneoplastic hypoglycemia. with hepatobiliary neoplasia include hypoalbuminemia,
Physical examination may reveal the presence of a cra­ hyperglobulinemia, hypoglycemia, and elevated bile
nial abdominal mass affect in up to 75% of patients. acids. In cats, azotemia has been reported as the most
However, some massive tumors or nodular and diffuse common biochemical abnormality. Studies have not
tumors may not cause any obvious physical exam changes clarified the cause of the azotemia though it may repre­
and can be easily missed. Occasionally, a patient may sent concurrent and unrelated chronic renal disease.
become jaundiced secondary to a hepatobiliary tumor or
develop ascites. Overall, dogs and cats with malignant
tumors are more likely to become symptomatic than Imaging
those patients with benign tumors. Abdominal radiographs may be helpful at confirming the
presence of a large hepatobiliary mass but can easily miss
small, nodular or diffuse tumors. In some cases, radio­
Diagnosis graphs may show the presence of mineralization within
the biliary tree of dogs with bile duct carcinoma although
Laboratory Tests this is a rare and nonspecific finding. Therefore, ultra­
sound is the recommended method of imaging for both
There are no distinguishing complete blood count dogs and cats. Ultrasound also allows for the detection of
abnormalities found in patients with hepatobiliary intraabdominal metastasis, ascites, and the location of
tumors. Hematologic profiles most often show mild and the disease and its relationship to other anatomic struc­
nonspecific changes such as anemia, leukocytosis, and tures. Most importantly, ultrasound will allow us to
thrombocytosis. A mild, nonregenerative anemia is most determine the morphologic features (massive, nodular,
common (present in 20–53% of patients). The cause is or diffuse) of the tumor and help guide whether surgical
largely unknown but speculated to be secondary to ane­ resection should be attempted.
mia of chronic disease, red blood cell sequestration, Ultrasound images alone, however, are not adequate to
microangiopathic destruction through torturous tumor diagnose histologic tumor type. An ultrasound‐guided
vessels, or iron deficiency. A leukocytosis may also be fine needle aspiration (FNA) or needle biopsy is recom­
present and can be caused by inflammation or necrosis mended, and is especially useful in cases of nodular or dif­
of any large tumor. Thrombocytosis has been reported in fuse disease. An accurate diagnosis is possible using these
approximately 50% of dogs diagnosed with a massive techniques in approximately 60% of FNA samples and
HCC. The cause of this is not fully understood but is 90% of needle biopsy samples. Both of these procedures
speculated to be secondary to anemia, inflammatory are considered minimally invasive. In some cases, laparo­
cytokine production, chronic iron deficiency, or a para­ scopic biopsy may be considered more appropriate and is
neoplastic process. also an excellent means of determining histologic tumor
Similarly, serum biochemical profiles often show non­ type. In cases of massive tumors, it may not be clinically
specific changes. Liver enzyme elevations are commonly warranted to know the histologic diagnosis of a particular
found in dogs with hepatobiliary tumors but there is no tumor prior to proceeding with exploratory surgery since
association with the magnitude of elevation and the the mass will most likely be fully removed and biopsied
severity of disease. These abnormalities are also in no postoperatively anyway. Advanced imaging modalities
way specific to hepatobiliary neoplasia as many other such as computed tomography (CT) and magnetic reso­
clinical conditions can affect these values. There are, nance imaging (MRI) are the primary imaging modalities
however, some trends that may be helpful. Alkaline utilized in human medicine for hepatobiliary tumors but
phosphatase (ALP) and alanine aminotransferase (ALT) have not been fully evaluated in veterinary medicine.
are the most common values to be elevated in dogs with
primary hepatic neoplasia whereas aspartate ami­
notransferase (AST) and bilirubin are more commonly Therapy and Prognosis
elevated in metastatic neoplasia, with >90% of dogs hav­
ing elevations in more than one liver enzyme. In cats,
one study showed that ALT, AST, and bilirubin were Hepatocellular Carcinoma
higher in cats with malignant tumors compared to The prognosis for patients with HCC is dependent
benign tumors The ratio of liver values to one another primarily on the morphologic subtype. Massive HCC
has also been examined. An AST:ALT ratio of less than 1 generally carries a good prognosis as it is confined to one