November 28, 2023
Cytokeratins are a group of proteins called intermediate filaments that are normally found inside specialized epithelial cells that make up the lining of many internal and external surfaces of the body, such as the skin, organs, and glands. These proteins provide structural support and protect against mechanical stress, as well as help maintain their shape and function. Examples of cytokeratins include cytokeratin 5 (CK5), cytokeratin 7 (CK7), cytokeratin 8/18 (CK8/18), and cytokeratin 20 (CK20). The types of cytokeratins expressed by epithelial cells vary throughout the body.
Examples of cytokeratins expressed by normal, healthy cells in different parts of the body:
Cytokeratins are commonly expressed in many types of tumours that start from epithelial cells including a group of cancers called carcinomas. Examples of carcinomas that produce these proteins include breast cancer, lung cancer, pancreatic cancer, prostate cancer, and colorectal cancer, among others. However, it’s important to note that not all epithelial tumors express these proteins, and the specific pattern of protein expression can vary depending on the type of cancer. Some non-epithelial tumours can also express cytokeratins.
Cytokeratins are commonly used as markers to identify and classify different types of epithelial cells, and they play a key role in the diagnosis and classification of many types of cancer. Pathologists perform a test called immunohistochemistry (IHC) to look for cytokeratins inside a tissue sample.
Doctors wrote this article 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.