Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. Cytokeratin 19 is positive in adenocarcinoma of the lung, gastrointestinal tract, pancreas and biliary tract, breast, endometrium, transitional cell carcinoma, neuroendocrine tumours, papillary thyroid carcinoma, mesothelioma.