Neuroendocrine metastatic tumors of the liver resembling hepatocellular carcinoma.

Certain neuroendocrine tumors (NET) metastasized to the liver can resemble hepatocellular carcinoma (HCC) in cytological needle biopsy. Experience concerning the histologic characteristics of metastatic NET resembling HCC in core needle hepatic biopsies has been scarce. The aim of this study is to describe the histological criteria in seven metastatic NET that resembled HCC in core needle hepatic biopsy. From a total of 285 needle biopsies with primary or metastasized hepatic neoplasms, seven cases were selected originally diagnosed as HCC or HCC vs. NET metastasized to the liver. Fourteen needle biopsies of hepatocellular carcinomas were also studied for comparative purposes. In all of these neoplasms the diagnosis of endocrine tumor was confirmed by immunohistochemical studies and the following information was recorded: age, sex, radiological alterations, primary site of the NET, and follow-up. The following histological data were also recorded: fibrotic stroma associated or not with the neoplastic cells, growth pattern, form of the cells, cellular size, mitotic figures, nucleomegaly, apparent nucleoli, chromatin in salt and pepper, plasmacytoid cells, intranuclear inclusions, and biliary pigment. In conclusion, these characteristics were common in metastasized neuroendocrine tumors: extensive stromal fibrosis, slight to moderate atypia, hyperchromatic nuclei, plasmacytoid cells, and thin delicate strands of fibrovascular tissue supporting larger acinar groups of net cells. HCC had a more infrequent fibrotic stroma, moderate to marked atypia, and in some biopsies biliary pigment, intranuclear inclusions, and clear cells.