Utility of cytokeratin 20 in identifying the origin of metastatic carcinomas in effusions

Our plain-English summary of Utility of cytokeratin 20 in identifying the origin of metastatic carcinomas in effusions, by V. Ascoli, S. Taccogna, C.C. Scalzo, et al (Diagnostic Cytopathology, 1995).

The study

• Authors: V. Ascoli, S. Taccogna, C.C. Scalzo, F. Nardi
• Journal: Diagnostic Cytopathology
• Published: 1995;12(4):303-8
• Cited by: 28 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Using a commercially available monoclonal antibody (Ks20.1) and the avidin-biotin peroxidase method on cytospins and cell blocks, we analyzed cytokeratin (CK) 20 expression in 169 serous effusions. Cytoplasmic staining was observed in 44/151 malignant fluids. Colon, gastric, and pancreatic adenocarcinomas and mucinous ovarian tumors were most frequently positive. Single cases of transitional-cell and squamous cell carcinomas were reactive as well. Lung and breast cancers were mostly negative. Nonmucinous ovarian tumors were invariably unlabeled as were mesotheliomas and normal mesothelial cells. The study shows that CK 20 is valuable in distinguishing tumor cell origin in effusions. In particular, it identifies a set of carcinomas with the majority arising from the gastrointestinal tract, and represents a highly characteristic marker for colorectal cancer.

In plain English

This laboratory study, from Università La Sapienza in Rome, Italy, tested whether staining for a protein called cytokeratin 20 (CK 20) could help show which organ a cancer had spread from when cancer cells were found in body-cavity fluid. The authors stained 169 fluid samples: 77 pleural, 88 peritoneal and four pericardial. They came from 74 males and 95 females aged 12 to 86. The study did not look at asbestos exposure. CK 20 staining was found in 44 of 169 samples. Mesothelial cells, whether benign, reactive or malignant, did not stain, and none of the five mesotheliomas was positive. Staining was found in 42 of 128 metastatic adenocarcinomas. It was most common in cancers from the digestive tract, including 13 of 15 colorectal and 12 of 17 stomach cancers. Fewer lung cancers (7 of 42), breast cancers (1 of 12) and ovarian cancers (3 of 32) stained. The authors concluded that the CK 20 antibody can be added to the antibodies used in cytology, being relatively selective for gastrointestinal and especially colorectal cancers. They noted it was of more limited value in pleural fluid.

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 (immunocytochemical) study of stored and fresh body-cavity fluid samples
• Who was studied: 169 serous effusions (77 pleural, 88 peritoneal, 4 pericardial) from 74 males and 95 females aged 12 to 86, studied at a cytology laboratory in Rome, Italy. 151 fluids were malignant, including 5 mesotheliomas and 146 metastatic effusions; 18 were benign. Dates of collection are not given.
• Exposure: No asbestos or other environmental exposure was studied. The study examined staining with a commercial anti-cytokeratin 20 monoclonal antibody (Ks20.1), compared with two other antibodies (CK-MNF116 and BerEP4), on cytospins and cell blocks.
• Main results:
  • CK 20 staining was detected in 44 of 169 samples (26%) overall.
  • By fluid type, 12 of 77 pleural (15.5%) and 31 of 88 peritoneal (35.2%) samples were positive.
  • Benign, reactive and malignant mesothelial cells were consistently unstained; the mesotheliomas (5 cases) were CK 20 negative.
  • 42 of 128 metastatic adenocarcinomas (32.8%) were CK 20 positive.
  • All metastatic colorectal adenocarcinomas except two (13 of 15 in Table II) were CK 20 positive, most with strong labeling.
  • 12 of 17 stomach cancers were CK 20 positive (Table II).
  • Only 1 of 12 fluids from metastatic breast adenocarcinoma contained cells reactive for CK 20.
  • Only three metastatic ovarian cancers (of 32 ovarian cases) stained for CK 20.
  • 7 of 42 lung cancers were CK 20 positive (Table II). All four small-cell lung tumors were unreactive.
  • In peritoneal fluids, CK 20 positivity was more often seen in gastrointestinal adenocarcinomas (23/88) than in cancers from other primary sites (8/88).
  • In pleural fluids, positivity occurred in both gastrointestinal cancers and non-small-cell lung tumors, at 83% and 15% respectively.
• The authors' conclusion: The authors concluded that the commercial CK 20 antibody can be added to the antibodies commonly used in cytology to recognize a set of carcinomas causing metastatic effusions. They described it as relatively selective for gastrointestinal adenocarcinomas, particularly colorectal cancers, and said it might help predict the site of origin, particularly in peritoneal (ascitic) fluid.
• Limitations the authors state:
  • The authors said CK 20 is of more limited value in pleural fluids, because staining occurs in both gastrointestinal and non-small-cell lung cancers.
  • The authors said a CK 20-negative carcinoma effusion does not exclude colorectal cancer, though their results suggested this possibility is remote.
  • The authors said CK 20 staining in cancers from various organs highlights the difficulty of exactly identifying the primary site.
  • The authors called for further studies on whether CK 20 is consistently expressed in all tumors resembling intestinal-type epithelium.

Topics

Medical terms in this study, explained in our Lexicon: Carcinoma, Monoclonal Antibody, Cell Block, Adenocarcinoma, Squamous Cell Carcinoma, Mesothelioma, Mesothelial Cells, Colorectal Cancer.

Related studies

• Cytomorphologic features of metastatic urothelial carcinoma in serous effusions — C.C. Huang, A. Attele, et al. (2013)
• Cytokeratin 7 and cytokeratin 20 expression in epithelial neoplasms: a survey of 435 cases — P. Chu, E. Wu, et al. (2000)
• Cytomorphological profile of neoplastic effusions: an audit of 10 years with emphasis on uncommonly encountered malignancies — S. Gupta, P. Sodhani, et al. (2012)
• Keratins 7 and 20 as diagnostic markers of carcinomas metastatic to the ovary — C.C. Wauters, F. Smedts, et al. (1995)
• Immunocytochemical utility of claudin-4 versus those of Ber-EP4 and MOC-31 in effusion cytology — T. Oda, S. Ogata, et al. (2016)
• 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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