Introduction

Age predisposition

• Metastatic or systemic neoplasia: any age.
• Primary hepatobiliary neoplasia: older dogs >10 years:
  • Median age of dogs with benign disease is greater than those with malignant tumors.

Sex predisposition

• Males for hepatocellular carcinoma.

Special risks

• May have coagulopathy due to liver dysfunction.

Pathogenesis

Etiology

• None determined for dogs; hepatitis B or C viral infection and cirrhosis are factors in people.

Predisposing factors

• Intrahepatic bile duct carcinomas have been associated with liver fluke infestation.

Pathophysiology

• Normal hepatic architecture disrupted by neoplastic cells.
• If large areas of liver involved → hepatic dysfunction/failure.
• Neoplasm may obstruct biliary tree → jaundice.
• Neoplasm may cause portal hypertension → ascites.
• Primary hepatic tumors may be solitary lobar masses or multiple discrete nodules in more than one lobe.
• Metastatic neoplasms may be diffuse infiltrates or multifocal nodules.

Primary hepatobiliary tumors

• Hepatocellular carcinomamost common, less likely to metastasize.
• Bile duct adenocarcinoma(biliary cystadenoma or hepatobiliary cystoadenoma) is benign and the most common liver tumor. These are multicystic or spongiform structures containing clear or blood-tinged fluid.
• Bile duct carcinoma (cholangiocarcinoma) is the second most common primary malignant liver tumor. Approximately 60% have metastasized to lungs, lymph nodes and most commonly intestinal serosa (carcinomatosis) by the time of diagnosis.
• Other uncommon liver tumors are gall bladder adenocarcinoma, biliary carcinoid, hemangiosarcoma and leiomyosarcoma.
• Neoplasms of biliary tract origin are more common than those of hepatic cell origin.
• Tumors may be a single lobar mass or multiple discrete nodules involving one or more lobes.
• Vomiting may result from pressure on stomach or from hepatic dysfunction.
• Jaundice may result from hepatic dysfunction or obstruction of the biliary tree.
• Signs of liver failure are seen when the liver is extensively infiltrated, but not when the disease is confined to one lobe/area.

Metastatic neoplasia

• Infiltration may occur with:
  • Lymphoma Lymphoma.
  • Lymphoid leukemia Chronic lymphoid leukemia.
  • Mast cell tumor Skin: mastocytoma.
  • Plasma cell tumor.
  • Myeloid leukemia Chronic myeloid leukemia.
• The infiltration is diffuse and non-encapsulated → generalized hepatomegaly and liver dysfunction.
• Solid tumors may metastasize to the liver → multiple nodules throughout liver:
  • Pancreatic carcinoma Pancreas: neoplasia.
  • Mammary adenocarcinomas Mammary gland: neoplasia.
  • Intestinal adenocarcinomas Large intestine: neoplasia Small intestine neoplasia.

Myelipomas

• Tumor-like nodules composed of mature adipose tissue and bone marrow elements, may rarely occur in the liver.

Timecourse

• Often insidious onset.

Diagnosis

Treatment

Outcomes