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. CEA is an oncofetal glycoprotein normally expressed by colonic mucosa of fetal colon and to a lesser degree in adult colonic mucosa. CEA is highly expressed in different adenocarcinoma types of various origins. The overexpression of CEA in adenomas or premalignant lesions correlates with the grade of dysplasia and can be an indicator for malignant transformation.