The applicability of a keratin 7 monoclonal antibody in routinely Papanicolaou-stained cytologic specimens for the differential diagnosis of carcinomas

Our plain-English summary of The applicability of a keratin 7 monoclonal antibody in routinely Papanicolaou-stained cytologic specimens for the differential diagnosis of carcinomas, by J.H. Baars, J.L. De Ruijter, F. Smedts, et al (American Journal of Clinical Pathology, 1994).

The study

• Authors: J.H. Baars, J.L. De Ruijter, F. Smedts, C.C. Van Niekerk, L.G. Poels, C.A. Seldenrijk, F.C. Ramaekers
• Journal: American Journal of Clinical Pathology
• Published: 1994;101(3):257-61
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The monoclonal antibody OV-TL 12/30, which detects keratin 7, was tested for its usefulness in cytologic diagnosis by reincubating previously Papanicolaou-stained slides. For this purpose malignant effusions of 73 patients with histologically confirmed cancers of the colon, ovary, mesothelium, breast, lung, esophagus, pancreas, urinary bladder, stomach, kidney, and prostate were used. All malignant cells from ovarian adenocarcinomas were positive, whereas malignant cells from colonic adenocarcinomas and malignant mesotheliomas were negative. Adenocarcinomas of gastric, renal, pancreatic, esophageal, and mammary origin demonstrated variable staining. Transitional cell carcinomas were positive, whereas squamous and small cell lung carcinomas were negative. Because OV-TL 12/30 does not react with normal and atypical mesothelial cells in these preparations, this reagent is a valuable tool in distinguishing benign mesothelial cells and adenocarcinoma cells. The authors' results demonstrate that this antibody is an excellent tool in the differential diagnosis of malignant cells in effusions and can be used in routinely stained cytologic specimens to determine primary tumor localization. In addition to its ability to distinguish between ovarian and colonic adenocarcinomas, its negativity in mesotheliomas may prove helpful in several diagnostic considerations.

In plain English

This laboratory study, from the Department of Clinical Pathology in Delft, the Netherlands, tested whether OV-TL 12/30, an antibody that detects keratin 7, could help identify the type of cancer cells in fluid from the chest or abdomen. It did not study asbestos exposure. The authors re-stained previously Papanicolaou-stained slides from 73 malignant and 15 benign pleural and abdominal effusions from patients with histologically confirmed cancers diagnosed from 1987 to 1991. All 11 ovarian adenocarcinomas stained positive. All slides from mesothelioma (10 cases) were negative. Colonic and esophageal adenocarcinomas and squamous and small cell lung carcinomas were also negative. Gastric adenocarcinomas were all positive, while breast, pancreatic, transitional cell and renal cancers stained variably. Benign mesothelial cells showed only sporadic staining. Slides stained by the May-Grünwald-Giemsa method showed no reactivity. The authors noted that their lung series was too small for definitive conclusions about telling lung adenocarcinoma from squamous cell carcinoma. The authors concluded that the antibody may be extremely useful in determining the origin of malignant cells in effusions.

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 diagnostic study (immunocytochemistry) on archived cytology slides that had already been Papanicolaou-stained and were re-stained with a keratin 7 antibody
• Who was studied: 73 malignant and 15 benign pleural and abdominal effusions from patients with histologically confirmed cancers, diagnosed from 1987 to 1991. Files were from the Department of Clinical Pathology of the SSDZ, Delft, The Netherlands. The cancers included ovary, breast, lung, mesothelioma, stomach, colon, esophagus, pancreas, urothelium, kidney and prostate.
• Exposure: No asbestos or other environmental exposure was studied. The test applied was the keratin 7 monoclonal antibody OV-TL 12/30. A second keratin 7 antibody, RCK 105, was used for comparison.
• Main results:
  • All 11 ovarian adenocarcinomas were positive with OV-TL 12/30, usually with intense staining.
  • All mesothelioma slides were negative. Table 1 lists 10 mesothelioma cases (8 epithelial type, 2 papillary type), with 0 positive.
  • Malignant cells from colonic adenocarcinomas (9 cases in Table 1) and esophageal adenocarcinoma (1 case) did not stain.
  • Squamous cell and small cell lung carcinomas were negative. In bronchioalveolar cell carcinoma and pulmonary adenocarcinoma, most cells stained.
  • Gastric adenocarcinomas (11 cases in Table 1) were all positive, with strong to moderate reactivity and variable numbers of non-reacting tumor cells.
  • Of 4 pancreatic adenocarcinomas, 2 were negative and 2 showed variable staining.
  • Breast adenocarcinoma cells showed a variable pattern: usually intense staining, but only a few cells stained in two cases.
  • Transitional cell carcinomas showed variable staining. In renal cell carcinoma only a few malignant cells stained.
  • OV-TL 12/30 was negative in malignant mesothelial cells and only sporadically positive in benign mesothelial cells. Table 1 lists 3 positive of 15 benign mesothelial cell cases.
  • On 10 unstained acetone-fixed control slides, RCK 105 stained most benign mesothelial cells, while OV-TL 12/30 generally did not.
  • Slides previously stained with May-Grünwald-Giemsa (MGG) showed no immunoreactivity.
• The authors' conclusion: The authors concluded that OV-TL 12/30 and keratin 7 antibodies may be extremely useful in determining the origin of malignant cells in effusions, and that its added value is its reactivity with routinely fixed, Papanicolaou-stained slides.
• Limitations the authors state:
  • The series was too small for definitive conclusions on distinguishing lung adenocarcinoma from squamous cell carcinoma.
  • The antibody did not work on MGG-stained slides. The authors said protocols for those slides would make it more useful.
  • Unstained acetone-fixed slides were harder to interpret because of background reactivity.
  • The antibody's value is in classifying malignant cells, not in screening effusions for missed cancer cells.

Topics

Medical terms in this study, explained in our Lexicon: Monoclonal Antibody, Differential Diagnosis, Carcinoma, Mesothelium, Adenocarcinoma, Malignant Mesothelioma, Mesothelial Cells, Mesothelioma.

Related studies

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• Keratins 7 and 20 as diagnostic markers of carcinomas metastatic to the ovary — C.C. Wauters, F. Smedts, et al. (1995)
• Distinct keratin patterns demonstrated by immunoperoxidase staining of adenocarcinomas, carcinoids, and mesotheliomas using polyclonal and monoclonal anti-keratin antibodies — H.J. Kahn, P.S. Thorner, et al. (1986)
• PAX8 Expression in a Subset of Malignant Peritoneal Mesotheliomas and Benign Mesothelium has Diagnostic Implications in the Differential Diagnosis of Ovarian Serous Carcinoma — D.B. Chapel, A.N. Husain, et al. (2017)
• 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)
• The distribution of vimentin and keratin in epithelial and nonepithelial neoplasms. A comprehensive immunohistochemical study on formalin- and alcohol-fixed tumors — N. Azumi, H. Battifora (1987)

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