Hepatic mesenchymal hamartoma in children: immunohistochemical study, ultrastructural and DNA flow cytometric analysis of a case.

Mesenchymal hamartoma is a rare liver lesion. This lesion was Sound in a 7-month-old girl with high serum alphafoetoprotein serum levels and was composed of loose connective tissue containing a certain number of epithelial cells of biliary or hepatic origin. Immunohistochemical studies showed that cytokeratins 7 and 19 were localized in bile duct epithelium. The ultrastructural study showed that the hamartoma was composed of well differentiated ductal structures surrounded by a myxoid mesenchyma with cysts formed either from degenerative mesenchymal areas or from dilated ducts. Flow cytometric analysis of nuclei from frozen tissue revealed that the lesion was DNA aneuploid, with a DNA index of 1,28.