Hepatocyte Specific Antigen (HSA or Hep Par 1) has been demonstrated consistently in the vast majority of Hepatocellular Carcinomas. Studies have shown the utility of HSA in the differential diagnosis of Hepatocellular Carcinoma, Cholangiocarcinoma and Hepatoblastomas. Hepatocyte Specific Antigen recognizes both benign and malignant liver derived tissues including such tumors as Hepatoblastoma, Hepatocellular Carcinoma, and Hepatic Adenoma.