Immunocytochemistry of CD146 is useful to discriminate between malignant pleural mesothelioma and reactive mesothelium

Our plain-English summary of Immunocytochemistry of CD146 is useful to discriminate between malignant pleural mesothelioma and reactive mesothelium, by A. Sato, I. Torii, Y. Okamura, et al (Modern Pathology, 2010).

The study

• Authors: A. Sato, I. Torii, Y. Okamura, T. Yamamoto, T. Nishigami, T.R. Kataoka, M. Song, S. Hasegawa, T. Nakano, T. Kamei, T. Tsujimura
• Journal: Modern Pathology
• Published: 2010;23(11):1458-66
• Cited by: 65 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Malignant pleural mesothelioma is a refractory tumor with poor prognosis associated with asbestos exposure. Pleural effusion is frequently observed in patients with malignant pleural mesothelioma, and cytological analysis is effective to detect malignant pleural mesothelioma. However, cytological discrimination between malignant pleural mesothelioma and reactive mesothelium is often difficult. Increased expression of CD146, a cell adhesion molecule, has been reported to be closely associated with an advanced stage of malignant melanoma, prostate cancer, and ovarian cancer. In this study, to evaluate the diagnostic utility of CD146 for discrimination between malignant pleural mesothelioma and reactive mesothelium, we examined immunocytochemical expression of CD146 in malignant pleural mesothelioma and reactive mesothelium using two clones of CD146 antibody, OJ79 and EPR3208, on smear specimens of effusion fluids. Immunocytochemical stains were semiquantitatively scored on the basis of immunostaining intensity (0, negative; 1, weak positive; 2, moderate positive; and 3, strong positive). CD146 expression was detected in 15 of 16 malignant pleural mesothelioma with median immunostaining score of 3 by OJ79, and in 19 of 21 malignant pleural mesothelioma with median immunostaining score of 2 by EPR3208. Strong immunoreactivity of CD146 was observed at the apposing surfaces of cell-cell interactions on the plasma membrane of mesothelioma cells. In addition, one OJ79-negative case of malignant pleural mesothelioma was positive for CD146 by EPR3208 and two EPR3208-negative cases of malignant pleural mesothelioma were CD146 positive by OJ79, showing that all 23 malignant pleural mesothelioma cases were positive for CD146 by either OJ79 or EPR3208. On the other hand, CD146 expression was undetectable in all reactive mesothelium cases by OJ79 and EPR3208. The sensitivity of OJ79 and EPR3208 was 94 and 90%, respectively, and the specificity was 100% for both clones. We propose that CD146 is a sensitive and specific immunocytochemical marker enabling differential diagnosis of malignant pleural mesothelioma from reactive mesothelium.

In plain English

This laboratory study from Japan tested whether staining cells for a protein called CD146 could help tell malignant pleural mesothelioma apart from reactive mesothelium (non-cancerous lining cells reacting to other illnesses) in body-fluid samples. The authors stained cell smears from 51 cases, 23 with malignant pleural mesothelioma and 28 with reactive mesothelium, using two antibodies against CD146, called OJ79 and EPR3208. Not every case was tested with both. OJ79 detected CD146 in 15 of 16 mesothelioma specimens and in none of 11 reactive mesothelium cases. EPR3208 detected it in 19 of 21 mesothelioma specimens and in none of 21 reactive cases. All 23 mesothelioma cases were positive with at least one of the two antibodies. The reported sensitivity was 94% for OJ79 and 90% for EPR3208, and the specificity was 100% for both. The authors noted that CD146 was also present in adenocarcinoma cells in pleural effusions, so the test cannot separate mesothelioma from metastatic adenocarcinoma. The study did not look at asbestos exposure. The authors concluded that CD146 is a sensitive and specific marker for distinguishing malignant pleural mesothelioma from reactive mesothelium.

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: Diagnostic laboratory study: immunocytochemical staining of fluid cell smears from patients with and without mesothelioma, comparing two CD146 antibodies
• Who was studied: 51 cases: 23 malignant pleural mesothelioma (22 epithelioid, 1 biphasic; 22 men and 1 woman, aged 44 to 92, median 67) and 28 reactive mesothelium (19 men and 9 women, aged 44 to 96, median 72). Specimens came from pleural, peritoneal or pericardial effusions and pleural washing fluids at the Hospital of Hyogo College of Medicine, plus four smears from Yamaguchi Grand Medical Center, Japan. The reactive cases were patients with conditions such as lung cancer, hepatocellular carcinoma, pneumonia, heart failure and pleural effusion of uncertain cause. Study dates were not given.
• Exposure: Not studied. The article does not report asbestos exposure for these patients. The factor tested was CD146 staining with two antibodies (OJ79 and EPR3208), compared with staining for EMA (epithelial membrane antigen).
• Main results:
  • Malignant pleural mesothelioma specimens: CD146 was detected in 15 of 16 with OJ79 (median staining score 3) and in 19 of 21 with EPR3208 (median staining score 2)
  • Reactive mesothelium cases: CD146 was undetectable in all 11 of 11 cases tested with OJ79
  • Reactive mesothelium cases: CD146 was undetectable in all 21 of 21 cases tested with EPR3208
  • All 23 malignant pleural mesothelioma cases were CD146 positive with at least one of the two antibodies
  • Sensitivity for malignant pleural mesothelioma was 94% for OJ79 and 90% for EPR3208; specificity was 100% for both
  • CD146 staining scores with both antibodies were significantly higher in malignant pleural mesothelioma than in reactive mesothelium (p less than 0.001)
  • EMA comparison: EMA was detected in 19 of 20 (95%) malignant pleural mesothelioma cases tested. In reactive mesothelium, 23 of 26 (88%) cases were negative for both EMA and CD146, and the other 3 were EMA positive and CD146 negative.
• The authors' conclusion: The authors proposed that CD146 is a sensitive and specific staining marker for distinguishing malignant pleural mesothelioma from reactive mesothelium.
• Limitations the authors state:
  • CD146 was also found in adenocarcinoma cells in pleural effusions, so the authors stated that CD146 staining cannot be used to tell malignant pleural mesothelioma from metastatic adenocarcinoma in the chest cavity

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Mesothelium, Prognosis, Asbestos Exposure, Pleural Effusion, Ovarian Cancer, Mesothelioma, Differential Diagnosis.

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