CEA or Carcinoembryonic antigen is a structural glycoprotein. CEA is very useful in the differentation of pulmonary adenocarcinoma from mesothelioma. CEA is expressed in epithelial cell membranes and in the cytoplasm of the cells in almost all cases of colorectal adenocarcinoma. CEA is particularly useful in localisation of a tumour to the digestive system.

The staining pattern of CEA is Membraneous and Cytoplasmic as shown below.

Picture 1 – CEA positivity in Colon Carcinoma

 

CEA has several different applications. Below are a few examples.

Tumour or cell type	CEA + or -
Colorectal Adenocarcinoma	Positive
Medullary thyroid carcinoma	Positive
Breast Carcinoma	Negative
Prostate Carcinoma	Negative