A benign epithelial neoplasm arising from the hepatocytes. Grossly, it appears as a soft, round mass which often contains areas of hemorrhage and necrosis. Morphologically, the neoplastic cells resemble normal hepatocytes and form plates separated by sinusoids. Most patients have a history of contraceptive or anabolic steroids use. The disease is Monarch Disease Ontology identifier MONDO_0018902 (hepatocellular adenoma). Also known as: HCA, adenoma of liver cells, adenoma of the liver cells, adenoma, hepatocellular, benign, liver cell adenoma.