In 1958, Edmonson reported finding only two adenomas among 50,000 autopsy specimens. Currently, decreases in dosages and the types of hormones contained in OCPs have led to a reduction in incidence.
Hepatocellular adenomas are large, fleshy, well circumscribed, and encapsulated tumors.
They consist of sheets of hepatocytes without bile ducts or portal areas. Lesions are prone to central necrosis and hemorrhage because the vascular supply is limited to the surface of the tumor. It is believed that the pathogenesis is related to a generalized vascular ectasia that develops due to oral contraceptive and related synthetic steroid exposure on the vasculature of the liver. It is also proposed that estrogen may exert an influence via estrogen receptors on hepatocytes. However, this remains controversial.