Hepatobiliary cystadenoma with mesenchymal stroma.

In a detailed review of cystic hepatobiliary neoplasms, we identified a subset of 50 cases in which tumors were characterized by the presence of a mesenchymal cell layer interposed between an inner epithelial lining and an outer connective tissue layer. We have recently seen three such patients, making a total of 53 patients reported in the English literature. All of the patients were female, 44 of whom, with an average age of 41 years, had benign tumors. The average age of the remaining nine patients was 57 years and these patients had malignant tumors. In seven patients, the malignancy arose from the epithelial layer, but in two patients sarcomatous changes were identified in the mesenchymal tissues. The older age of the patients with malignant tumors with adequate serial biopsies in two cases supported the thesis that malignant transformation may occur in the benign tumors. Moreover the location of the tumor in one of our patients in whom the resected tumor was associated with anomalous right hepatic ducts and portal veins supported the theory that these tumors develop embryologically from nests of primitive hepatobiliary endodermal and mesodermal cells. Although surgical treatment was performed in all patients, 25% of the patients with benign hepatobiliary cystadenoma with mesenchymal stroma (CMS), and 33% of the patients with malignant CMS had tumor recurrence after primary resection. Ninety per cent of these patients had an incomplete resection at the time of their initial operations. Forty-four per cent of the patients with malignant CMS died after a mean follow-up of 17 months. We conclude that CMS (Edmonson's tumor) occurs uniquely in young female patients, develops from nests of primitive embryonal cells, has the potential for malignant transformation, and should be completely resected at primary operation to avoid recurrence.