Test Details: Immunohistochemical testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. CA19-9 is normally present on the apical surface of the ductal epithelium of the breast, salivary, and sweat glands beside the glands of gastrointestinal mucosa. CA19-9 strongly stains pancreatic, hepatobiliary, and gastrointestinal adenocarcinomas.It is also expressed in ovarian and lung adenocarcinoma, renal cell carcinoma, transitional cell carcinoma, mucoepidermoid carcinoma,etc.