CDX-2

by Jason Wasserman MD PhD FRCPC
June 12, 2022


What is CDX-2?

CDX-2 is a specialized type of protein called a transcription factor. CDX-2 is called a transcription factor because it helps guide the transcription or expression of genes required for the normal development of a cell.

What types of cells normally make CDX-2?

CDX-2 is normally made by cells in the small intestine and colon. Intestinal metaplasia is a non-cancerous process where cells outside of the small intestine or colon change to become more like the cells in the small intestine or colon. Cells that show intestinal metaplasia will also make CDX-2.

What types of tumours produce CDX-2?

Most tumours that start in the small intestine and colon make CDX-2. These tumours include adenocarcinoma of the colon, adenocarcinoma of the small intestine, well differentiated neuroendocrine tumour of the small intestine, poorly differentiated neuroendocrine carcinoma of the small intestine, well differentiated neuroendocrine tumour of the colon, and poorly differentiated neuroendocrine carcinoma of the colon. Some tumours from the esophagus, stomach, gallbladder, ovary, cervix, and the sinonasal tract can also make CDX-2. These types of tumours often show a change called intestinal differentiation. This means that the tumour cells are looking and behaving more like cells from the small intestine or colon.

Why do pathologists test for CDX-2?

The most common reason that pathologists test for CDX-2 is to see if the cells they are seeing under the microscope are from a part of the digestive tract that usually makes CDX-2. This is especially important when examining a tumour as it can help determine where the tumour started.

How do pathologists test for CDX-2?

Pathologists use a test called immunohistochemistry to ‘see’ CDX-2 inside cells. The protein is normally found in a part of the cell called the nucleus. Pathologists describe this result as ‘nuclear reactivity’.

What does positive for CDX-2 mean?

Positive for CDX-2 means that the cells in the tissue sample were making this protein. Normal, healthy cells from the small intestine and colon will be positive for CDX-2. Most tumours from the small intestine and colon and some tumours from the esophagus, stomach, gallbladder, ovary, cervix, and the sinonasal tract will also be positive for CDX-2.

What does negative for CDX-2 mean?

Negative for CDX-2 means that the cells in the tissue sample were not making this protein. Other than the cells in the small intestine and colon, most other normal cells do not produce CDX-2.

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