Are oral contraceptive-associated liver cell adenomas premalignant?

From January 1977 to June 1990, 1,670 patients with a liver mass or masses underwent transabdominal fine needle aspiration biopsy of the liver. Of those cases, 99 were diagnosed cytologically as "hepatocellular carcinoma" and 9 as "consistent with liver cell adenoma." Among the 99 patients with hepatocellular carcinoma, 3 were users of oral contraceptives. The nine patients with liver cell adenoma were all users of oral contraceptives. Of them, two developed foci or areas of liver cell dysplasia within the adenomas. The mean periods of oral contraceptive use among these three groups of patients were different. It appeared that patients started to develop liver cell adenoma after five years of oral contraceptive use (mean, 6.3 years). Foci or areas of liver cell dysplasia began to arise within liver cell adenomas after 8 years of oral contraceptive use (mean, 9 years), and the patients started to develop hepatocellular carcinoma after 10 years of contraceptive use (mean, 11 years). The cytologic features of liver cell dysplasia strikingly mimicked those of hepatocellular carcinoma. From this study, the foci or areas of liver cell dysplasia appear to be the missing link responsible for the transformation of liver cell adenoma to carcinoma. It is believed that liver cell adenomas are not premalignant and may undergo reversible change after withdrawal of causative agents, whereas foci or areas of liver cell dysplasia within the adenomas are irreversible, premalignant changes and may transform into hepatocellular carcinoma.