Mesenchymal Hamartoma of the Liver

Abstract

Mesenchymal hamartoma of the liver is an uncommon benign lesion that appears as a large abdominal mass, almost exclusively in the first 2 years of life. It has been believed that this lesion is not a true neoplasm but rather a kind of hamartomatous lesion arising from the connective tissue of the portal tracts at some point in their development. Minor components of liver cells and bile ducts are considered a result of entrapment. We report a case of typical cystic mesenchymal hamartoma in a 17-month-old boy who first presented with an abdominal mass at 7 months of age. The tumor was located in the right lobe, 17 cm in maximum diameter, and was largely cystic and partly solid, The cysts were multiloculated and lined by a single layer of tall columnar partly ciliated epithelium, and the irregular admixture of mature liver cell islands and intervening loose myxoid stroma was evident. Electronmicroscopic study revealed that the lining epithelium was the same as that of the bile duct, and the liver cell element was so mature that it couldn't be differentiated from normal hepatocytes. The stroma cell resembled fibroblast.