Hepatobiliary Neoplasia

Introduction:  Hepatobiliary neoplasia, either primary or metastasis, is a relatively common cause of hepatic disease in the cat and dog.  Pathologically, hepatobiliary neoplasia typically occurs in one of three patterns: 

• a focal mass in one liver lobe,  
• multinodular (affecting one or multiple lobes), or 
• diffuse throughout the liver.   

Cats are more likely to have multi-lobular involvement.  Tumors arising in the liver, biliary tract, or adjacent tissues can also produce bile duct obstruction.

 
A multinodular hepatic tumor.

Types of Hepatic Neoplasia: 

• Primary hepatic tumors:  Primary hepatobiliary tumors may be benign or malignant and usually arise from the hepatocytes (hepatocellular adenomas or carcinomas) or the biliary epithelium (cholangiocellular adenomas or adenocarcinomas).  Primary tumors of the liver are rare in cats.  Primary endothelial tumors such as hemangiosarcomas may also occur, but with a much lower incidence than either hepatobiliary tumors or metastatic tumors.  See histopathology slides of biliary carcinoma.

• Metastatic hepatic tumors:  Metastatic tumors of the liver are approximately three times more common than primary tumors.  The most common metastatic tumors are  hemangiosarcomas, malignant lymphosarcoma, carcinomas, and adenomas.  In all species, metastatic lesions of the liver may originate from the pancreas, gastrointestinal tract, mammary glands, adrenal glands, bone, and elsewhere.  

Signalment:  Primary hepatic neoplasia is more common in the dog.  Only 1-3% of feline hepatic tumors are derived from the hepatic tissue.  Of those feline tumors, bile duct adenoma is the most commonly reported.  As with most neoplasia, hepatic cancer is most common in older adult animals.  The exception is lymphosarcoma which can be FeLV associated in young cats.

Presenting clinical signs:  

• Many signs associated with hepatobiliary neoplasia are non-specific for liver dysfunction, and are frequently not noticed until late in the disease process.  

• Primary presenting complaints in cats are anorexia and lethargy.  

• Primary presenting complaints in dogs are vomiting, polyuria, polydipsia, and weight loss.

• Since many hepatobiliary tumors are metastatic in origin, clinical signs may also correspond with dysfunction of the system in which the primary tumor is located or other sites of metastasis.

• Physical examination may reveal the presence of a cranial abdominal mass and marked hepatomegaly.  

• Hemoperitoneum or ascites may occur secondary to rupture of the tumor.  

• Icterus is an infrequently recognized clinical sign in neoplastic disease unless the tumor causes obstruction of the common bile duct.

Clinical Pathology:  

• Laboratory data is non-specific for hepatic dysfunction.  

• Cats with hepatobiliary neoplasia many have mild-marked increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST).  However cats rarely have increases in alkaline phosphatase (ALP).  

• Hematology may show anemia of chronic disease (non-regenerative, normocytic, normochromic).  

• Coagulopathies, as indicated by increased OSPT and APTT, are rarely identified in cases of hepatobiliary neoplasia.  They should always be considered when planning invasive procedures in cats with evidence of significant hepatic dysfunction. 

• Abdominal radiographs may support the physical exam findings of hepatomegaly and peritoneal effusion, however transabdominal ultrasound will yield more information regarding the characteristics of the changes (i.e. focal, nodular, or diffuse changes in the hepatic parenchyma).

For more information  . . .

• Strombeck, D.  Strombeck's Small Animal Gastroenterology, 3rd Edition.  1996.