IMP3/L523S, a novel immunocytochemical marker that distinguishes benign and malignant cells: the expression profiles of IMP3/L523S in effusion cytology

Our plain-English summary of IMP3/L523S, a novel immunocytochemical marker that distinguishes benign and malignant cells: the expression profiles of IMP3/L523S in effusion cytology, by K. Ikeda, G. Tate, T. Suzuki, et al (Human Pathology, 2010).

The study

• Authors: K. Ikeda, G. Tate, T. Suzuki, T. Kitamura, T. Mitsuya
• Journal: Human Pathology
• Published: 2010;41(5):745-50
• Cited by: 39 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Differentiating reactive mesothelial cells from metastatic carcinoma and malignant mesothelioma is critical in effusion cytology. Numerous immunohistochemical/cytochemical reports use various antibodies in effusion samples, and most antibodies differentiate metastatic adenocarcinoma from malignant mesothelioma, but no antibodies help distinguish malignant mesothelioma from reactive mesothelial cells. A mouse monoclonal antibody (IMP3/L523S) against KOC is a 580-amino acid oncofetal RNA-binding protein containing 4 K homology domains. IMP3/L523S has been identified in several human malignant tumors. The immunocytochemical staining profile of IMP3 was determined in 95% alcohol-fixed cytologic effusion specimens. A total of 229 cases of pleural and peritoneal effusion cytospecimens were evaluated for the study, including 39 benign effusions with reactive mesothelial cells and 190 metastatic malignant effusions. IMP3 immunoreactivity was observed in 2 (5.1%) of 39 cases of reactive mesothelial cells, 138 (72.6%) of 190 cases of malignant effusion, 4 (36.4%) of 11 cases of malignant mesothelioma, 106 (75.7%) of 140 cases of metastatic adenocarcinoma, and 8 (100%) of 8 cases of squamous cell carcinoma. The overall specificity for the diagnosis of malignancy was 94.9%, whereas the sensitivity was 72.6%. In the peritoneal effusions, the sensitivity for the diagnosis of metastatic adenocarcinoma to distinguish reactive mesothelial cells was 92.3%. In conclusion, IMP3 staining is present in many carcinomas and is not a useful marker for distinguishing between carcinomas arising in different organs. However, the IMP3 antibody is a highly specific marker for malignant lesions, and thus, IMP3 staining is useful for distinguishing neoplastic cells from reactive mesothelial cells in effusion samples.

Copyright 2010 Elsevier Inc. All rights reserved.

In plain English

This laboratory study from a pathology department in Yokohama, Japan, tested whether staining with an antibody called IMP3/L523S could separate cancer cells from benign 'reactive' mesothelial cells in pleural and peritoneal fluid samples. The authors stained 229 samples: 39 benign samples with reactive mesothelial cells and 190 malignant samples, including 11 malignant mesothelioma cases and 140 adenocarcinoma cases. The stain was positive in 2 of 39 benign samples (5.1%), 138 of 190 malignant samples (72.6%), 4 of 11 mesothelioma samples (36.4%) and 106 of 140 adenocarcinoma samples (75.7%). Overall specificity for malignancy was 94.9% and sensitivity was 72.6%. Breast cancer samples were rarely positive (2 of 16). The study did not examine asbestos exposure and did not say whether the mesothelioma cases were pleural or peritoneal. The authors concluded that IMP3 is highly specific for malignant cells and useful for distinguishing them from reactive mesothelial cells. They also concluded it is not useful for telling apart carcinomas arising in different organs. They attributed their lower sensitivity, compared with an earlier study, to the small number of cells in their samples.

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 of immunocytochemical staining on effusion (body fluid) specimens
• Who was studied: 229 pleural and peritoneal effusion specimens: 39 benign effusions with reactive mesothelial cells and 190 malignant effusions. The malignant cases included 11 malignant mesothelioma cases, adenocarcinomas from many organs, lymphomas and leukemias. The authors' department was at Showa University Fujigaoka Hospital, Yokohama, Japan. The study period was not stated.
• Exposure: Not an exposure study; no asbestos or occupational exposure was examined. The test evaluated was staining with an anti-human IMP3 antibody on Papanicolaou-stained, 95% alcohol-fixed cytospin smears that were then destained.
• Main results:
  • IMP3 staining was positive in 2 (5.1%) of 39 benign samples with reactive mesothelial cells and in 138 (72.6%) of 190 malignant samples.
  • Staining was positive in 4 (36.4%) of 11 malignant mesothelioma samples, 106 (75.7%) of 140 adenocarcinoma samples, and 8 (100%) of 8 squamous cell carcinoma samples.
  • Overall specificity for diagnosing malignancy was 94.9% and sensitivity was 72.6%. In peritoneal effusions, sensitivity for distinguishing adenocarcinoma from reactive mesothelial cells was 92.3%.
  • Despite low staining of mesothelioma (36.4%), the authors reported a significant difference between mesothelioma and reactive mesothelial cells (P = .0049).
  • Staining was positive in 2 (12.5%) of 16 breast cancer samples. Breast carcinoma was the exception where staining did not differ from reactive mesothelial cells.
  • By primary site, staining was positive in 26 of 38 lung cancer samples, 30 of 36 gastric-intestinal cancer samples, 23 of 23 liver-biliary tract-pancreatic cancer samples, 36 of 39 ovary and uterine corpus cancer samples, and 11 of 19 malignant lymphoma and leukemia samples.
• The authors' conclusion: The authors concluded that IMP3 staining is present in many carcinomas and is not useful for distinguishing carcinomas from different organs. They concluded it is a highly specific marker for malignant lesions and useful for distinguishing neoplastic cells from reactive mesothelial cells in effusion samples.
• Limitations the authors state:
  • Sensitivity was lower than in an earlier study using cell blocks. The authors attributed this most likely to the small number of cells available in their samples.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Cytology, Reactive Mesothelial Cells, Carcinoma, Malignant Mesothelioma, Adenocarcinoma, Monoclonal Antibody, Squamous Cell Carcinoma.

Related studies

• Diagnostic usefulness of EMA, IMP3, and GLUT-1 for the immunocytochemical distinction of malignant cells from reactive mesothelial cells in effusion cytology using cytospin preparations — K. Ikeda, G. Tate, et al. (2011)
• MMP-7 is a highly specific negative marker for benign and malignant mesothelial cells in serous effusions — B. Davidson, H.T. Stavnes, et al. (2016)
• Immunocytochemical utility of claudin-4 versus those of Ber-EP4 and MOC-31 in effusion cytology — T. Oda, S. Ogata, et al. (2016)
• Morphologic and immunocytochemical performances of effusion cell blocks prepared using 3 different methods — X. Jing, Q.K. Li, et al. (2013)
• Cytological differential diagnosis among adenocarcinoma, epithelial mesothelioma, and reactive mesothelial cells in serous effusions by immunocytochemistry — X.Y. Su, G.D. Li, et al. (2011)
• Calretinin. A selective marker of normal and neoplastic mesothelial cells in serous effusions — M.C. Barberis, M. Faleri, et al. (1997)

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