Cytokeratin 7 and cytokeratin 20 expression in epithelial neoplasms: a survey of 435 cases

Our plain-English summary of Cytokeratin 7 and cytokeratin 20 expression in epithelial neoplasms: a survey of 435 cases, by P. Chu, E. Wu, L.M. Weiss (Modern Pathology, 2000).

The study

• Authors: P. Chu, E. Wu, L.M. Weiss
• Journal: Modern Pathology
• Published: 2000;13(9):962-72
• Cited by: 713 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Cytokeratin 7 (CK 7) and cytokeratin 20 (CK 20) are low molecular weight cytokeratins. Their anatomic distribution is generally restricted to epithelia and their neoplasms. We surveyed 435 epithelial neoplasms from various organ systems by immunohistochemistry using CK 7 and CK 20 monoclonal antibodies. Expression of CK 7 was seen in the majority of cases of carcinoma, with the exception of those carcinomas arising from the colon, prostate, kidney, and thymus; carcinoid tumors of the lung and gastrointestinal tract origin; and Merkel cell tumor of the skin. The majority of cases of squamous cell carcinoma of various origins were negative for CK 7, except cervical squamous cell carcinoma, in which 87% of cases were positive. Approximately two thirds of cases of malignant mesothelioma were CK 7-positive. CK 20 positivity was seen in virtually all cases of colorectal carcinomas and Merkel cell tumors. CK 20-positive staining was also observed in cases of pancreatic carcinomas (62%), gastric carcinoma (50%), cholangiocarcinomas (43%), and transitional cell carcinomas (29%). The expression of CK 20 was virtually absent in carcinomas from other organ systems and in malignant mesothelioma. CK 7- and CK 20-negative epithelial neoplasms included adrenal cortical carcinoma, germ cell tumor, prostate carcinoma, renal cell carcinoma, and hepatocellular carcinoma.

In plain English

This laboratory study, from the City of Hope National Medical Center in California, looked at how often two proteins, cytokeratin 7 (CK 7) and cytokeratin 20 (CK 20), appeared when stored tumor tissue was stained with antibodies. The authors described 435 tumor cases from many organs, taken from their surgical pathology files, including 17 malignant mesotheliomas. A tumor counted as positive if more than 5% of its cells stained. Of the 17 malignant mesotheliomas, 11 (65%) were positive for CK 7 and none were positive for CK 20. The other 6 (35%) were negative for both. All 20 colon adenocarcinomas were CK 20-positive. All lung (10 of 10) and ovarian (24 of 24) adenocarcinomas were CK 7-positive. Prostate and adrenal cortical carcinomas were negative for both. The authors' view was that the two stains are best used together when trying to identify a poorly differentiated carcinoma. The study did not examine asbestos exposure, and it did not say where the mesotheliomas arose. The authors noted that mucinous tumors were not specifically examined.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory (immunohistochemistry) survey of archived tumor specimens
• Who was studied: 435 tumor cases from many organs, selected from the surgical pathology files of the City of Hope National Medical Center, Duarte, California. They included 17 malignant mesotheliomas. Dates are not given.
• Exposure: No asbestos or other exposure was studied. The study examined tumor staining with CK 7 and CK 20 antibodies. More than 5% stained tumor cells counted as positive.
• Main results:
  • Malignant mesothelioma: 11 of 17 cases (65%) were positive for CK 7.
  • Malignant mesothelioma: 0 of 17 cases were positive for CK 20.
  • Malignant mesothelioma: 6 of 17 cases (35%) were negative for both CK 7 and CK 20.
  • Colon adenocarcinoma: all 20 cases were positive for CK 20.
  • Lung adenocarcinoma (10 of 10) and ovarian adenocarcinoma (24 of 24) were all positive for CK 7.
  • Adrenal cortical carcinomas (10 of 10) and prostatic carcinomas (18 of 18), along with thymomas and epithelioid sarcomas, were negative for both CK 7 and CK 20.
• The authors' conclusion: The authors stated that CK 7 and CK 20 antibodies are best used together when trying to identify a poorly differentiated carcinoma. They cited other studies in support of this view.
• Limitations the authors state:
  • Mucinous tumors of ovarian, pancreatic or gastrointestinal origin were not specifically examined.
  • When comparing with an earlier study by Wang et al., the authors noted a different cut-off for positivity (5% versus 1%) and a different CK 20 antibody, which may partly explain differences between the two studies.

Topics

Medical terms in this study, explained in our Lexicon: Neoplasm, Immunohistochemistry, Monoclonal, Carcinoma, Squamous Cell Carcinoma, Malignant Mesothelioma, Germ Cell Tumor.

Related studies

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• Utility of cytokeratin 20 in identifying the origin of metastatic carcinomas in effusions — V. Ascoli, S. Taccogna, et al. (1995)
• E-cadherin and cytokeratin subtype profiling in effusion cytology — J. Han, M.K. Kim, et al. (2004)
• Expression of calretinin, thrombomodulin, keratin 5, and mesothelin in lung carcinomas of different types: an immunohistochemical analysis of 596 tumors in comparison with epithelioid mesotheliomas of the pleura — M. Miettinen, M. Sarlomo-Rikala (2003)
• Value of p63 and cytokeratin 5/6 as immunohistochemical markers for the differential diagnosis of poorly differentiated and undifferentiated carcinomas — O. Kaufmann, E. Fietze, et al. (2001)
• Wilms tumor 1/cytokeratin dual-color immunostaining reveals distinctive staining patterns in metastatic melanoma, metastatic carcinoma, and mesothelial cells in pleural fluids: an effective first-line test for the workup of malignant effusions — J.R. Conner, E.S. Cibas, et al. (2014)

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