Cytokeratin 7 (CK7)

MyPathologyReport
November 5, 2023

Cytokeratin 7 (CK7) is a protein made by epithelial cells in the thyroid gland, lungs, thymus, female reproductive organs, upper digestive tract, and head and neck. This type of protein is also made by most benign (noncancerous) and malignant (cancerous) tumours that start in these organ systems. After CK7 is made, it is held in the cytoplasm (body) of the cell. CK7 is a structural protein that helps epithelial cells maintain their shape.

Immunohistochemistry (IHC) is a test pathologists perform to see CK7-producing cells in a tissue sample. When combined with other immunohistochemical markers, this test allows pathologists to determine if the cells they are seeing under the microscope come from one of the organ systems that normally produces this protein. Cells that produce CK7 are typically described as ‘positive’ while those that do not produce the protein are described as ‘negative’.

This test is particularly helpful when examining a tumour under the microscope because tumours that come from the thyroid gland, lungs, thymus, female reproductive organs, upper digestive tract, and head and neck are more likely to produce CK7 while tumours from other locations are not. Pathologists use the results of this test combined with other features to make a diagnosis.

Examples of tumours that are positive for cytokeratin 7:

• Breast cancers such as invasive ductal carcinoma and ductal carcinoma in situ
• Stomach cancers such as adenocarcinoma
• Pancreatic cancers such as ductal adenocarcinoma
• Thyroid gland cancers such as papillary thyroid carcinoma, follicular carcinoma, and medullary carcinoma
• Endometrial cancers such as endometrioid carcinoma, serous carcinoma, and clear cell carcinoma
• Lung cancers such as adenocarcinoma

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.

Other helpful resources

Atlas of pathology