The Significance Of ERC Expression In Hepatic Primary Malignant Spindle Cell Tumors

Objective：To investigate the clinicopathologic characteristics of primary hepaticmalignant spindle cell tumors and the expression of ERG, FLI-1,CD34, CD31andfactor Ⅷ-related antigen (FⅧRAg) in hepatic malignant vascular tumors andexplore the significance of ERG in vascular tumors.Methods：A retrospective analysis was made on122cases of11types of primaryhepatic malignant spindle cell tumors，which were confirmed by histopathology andimmunohistochemistry. The expression and localization of ERG was examined in allmalignant vascular tumor specimens and compared to the known endothelialmarkers Fli-1, CD34, CD31and FⅧRAg by using immunohistochemical staining.The endothelial markers were also studied in a panel of non-vascular tumors. ERGgene translocation on paraffin-embedded tissue sections was detected by FISH.Results: Among122specimens of hepatic spindle cell tumors，there were24casesof angiosarcoma (19.6％)，38of epithelioid hemangioendothelioma (31.1％)，1ofhepatic Kaposi’s sarcoma（0.8%）,32cases of sarcomatoid carcinoma(26%)，8ofundiferentiated sarcoma (6．5％),3of leiomyosarcoma (6．5％),1ofrhabdomyoscarcoma (0.8%）,2of solitary fibrous tumor (1.6%),7of inflammatorymyofibroblastic tumor（5.7%）,5of malignant fibrous histiocytoma（4.1%），1offollicular dendritic cell sarcoma（0.8%）. While100%of the malignant vasculartumors, including24of angiosarcoma,38of epithelioid hemangioendothelioma,1ofhepatic Kaposi’s sarcoma were positive for ERG, the expression of other markerswas more variable. Fli-1was expressed in96%(61/63) of cases, CD34was in87.3%(55/63), CD31was80.9%(51/63) and FⅧRAg was expressed in41.2%(26/63) ofcases. Patients with angiosarcoma had the shorter median overall survibal (12.6months) than patients with epithelioid hemangioendothelioma (34.9months).Extrahepatic involvement and mitotic activity were all significantly correlated to the prognosis. Dual-color interphase FISH showed an intact ERG locus and lack of theERG gene translocationin the immunohistochemical ERG-positive vascular tumors.Conclusion Primary malignant vascular tumor was the most common type ofprimary spindle cell tumors in the liver．In hepatic angiosarcoma group, those withmultinodular tumor, without extrahepatic lesion, low grading of mitotic count, andtreated by surgical resection have a better prognosis. Extrahepatic involvement，necrosis, mitotic count grading, and Ki-67labelling index all showed significantcorrelation to the overall survival of hepatic epithelioid hemangioendothelioma.Mitotic count grading and extrahepatic involvement are independent prognosticfactors for overall survival of malignant vascular tumors in the liver. ERG is a moresensitive and specific diagnostic marker for hepatic malignant vascular tumors incomparison to Fli-1, CD34, CD31and FⅧRag. There is no evidence for ERG generearrangement in hepatic malignant vascular tumors.