Role of arginase 1 immunohistochemical marker in differentiating hepatocellular carcinoma from other primary and secondary carcinomas of the liver, a tissue microarray study

: Hepatocellular carcinoma (HCC) is the most prevalent type of primary cancer of the liver in adults represent about 80%-90% of all liver cancers. It is essential to differentiate primary HCC and intrahepatic cholangiocarcinoma and metastatic carcinoma. Arginase-1 was considered as the most sensitive and specific marker of benign and malignant hepatocyte. This study aimed to detect the diagnostic role of immunohistochemical expression of arginase-1 in differentiating HCC From cholangiocarcinoma and metastatic carcinomas of the liver in comparison with hepatocyte paraffin antigen -1 (HepPar-1) and Glypican 3. : This is a retrospective study was performed on 117 cases, 77 cases were diagnosed as HCC, 13 cases as cholangiocarcinoma and 27 cases as metastatic carcinomas in the liver. Cases obtained from surgical pathology laboratory at Gastroenterology Center, Mansoura University, Egypt during the period from 2014 to 2017. All the studied cases were immunostained with Arginase 1, Heppar 1and Glypican 3.: Arginase 1 was expressed in all 77 HCC cases with sensitivity (100%), while Arginase 1 was expressed only in 1 cholangiocarcinoma case and negative in other metastatic carcinomas with specificity(97.5%), the overall accuracy was (99.1%). On the other side, Glypican 3 was expressed in 36 out of 77 HCC cases with sensitivity (46.8%), while Glypican 3 was expressed in 3 out of 40 cholangiocarcinoma and other metastatic carcinomas with specificity (92.3%), overall accuracy (62.4%). Heppar 1 was expressed in 69 out of 77 HCC cases with sensitivity (89.6%), while Heppar 1 was negative in all cholangiocarcinoma cases and other metastatic carcinomas with specificity (100%). The overall accuracy was 93.2%.: Arginase 1 is the most sensitive and accurate marker in differentiating HCC from non HCC cases in liver, while heppar is most specific and second accurate marker in differentiating HCC from cholangiocarcinoma and metastatic carcinomas in the liver. Arginase-1 and HepPar-1, are the best markers regarding sensitivity and specificity for small liver biopsies.