Hepatocellular adenoma is a benign tumor of the liver that originate as an over-growth of epithelial cells. These benign tumors are slow progressing and nonmetastatic in nature, appearing as well-circumscribed and demarcated growth similar to nodular hyperplasia and can grow quite large. They are usually single, may be quite large (up to 20 cm) and often exhibit a pedunculated attachment.
Hepatocellular adenomas may go unnoticed because they rarely cause any clinical signs. Often, they are diagnosed as an incidental finding on ultrasonography. These tumors rarely cause physical symptoms until they interfere with normal hepatic function and may then cause abdominal distension, ascites, lethargy, anorexia and weight loss.
This condition is mostly seen in dogs ten years or older.