Benign tumors of the liver. Pathologic examination of 45 cases.

The histologic and clinical features of 45 benign tumors of the liver (excluding hemangiomas) were reviewed. They included 21 cases of focal nodular hyperplasia, 11 cases of hepatic cell adenoma, 12 cases of bile-duct adenoma and a single case of mesenchymal hamartoma. By adhering to published histologic criteria, the cases of focal nodular hyperplasia and hepatic cell adenoma could be readily separated. Although both focal nodular hyperplasia and hepatic cell adenoma occurred predominantly in women, focal nodular hyperplasia occurred at a greater mean age, was usually asymptomatic, and the lesions tended to be smaller (surgical cases) than hepatic cell adenoma. The latter usually were symptomatic. It is emphasized that focal nodular hyperplasia and hepatic cell adenoma are distinct lesions and are separable on histologic grounds. Although the names focal nodular hyperplasia and hepatic cell adenoma are retained, the authors cannot assert that one lesion is a neoplasm, the other a reactive condition, and prefer, instead, to leave this question unresolved.