Test Details: Immunohistochemical testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. AE1/AE3 is a widely used as pan-cytokeratin marker. It is positive in all epithelial tumours but few epithelial tumours are negative or weakly positive for this cocktail such as hepatocellular and renal cell carcinoma, adrenal cortical carcinoma, prostatic adenocarcinomas, and neuroendocrine tumours.