Glypican-1 immunohistochemistry does not separate mesothelioma from pulmonary adenocarcinoma

Our plain-English summary of Glypican-1 immunohistochemistry does not separate mesothelioma from pulmonary adenocarcinoma, by K. Chiu, L. Lee, S. Cheung, et al (Modern Pathology, 2018).

The study

• Authors: K. Chiu, L. Lee, S. Cheung, A.M. Churg
• Journal: Modern Pathology
• Published: 2018;31(9):1400-1403
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Immunohistochemistry (IHC) is used to help differentiate pleural mesothelioma from pulmonary adenocarcinoma in pleural biopsies and cytology specimens of pleural effusions due to overlapping morphologic features between these two malignancies. The aim of this study is to evaluate IHC glypican-1, a recently proposed marker for epithelioid mesothelioma, in our cohort of mesotheliomas and pulmonary adenocarcinoma. Tissue microarrays with duplicate cores from 33 cases of mesotheliomas (28 epithelioid type and five sarcomatoid type) and 21 cases of pulmonary adenocarcinoma were stained with glypican-1 antibody. The proportion of cases by tumor type showing staining with glypican-1 and the H-score for each tumor type were evaluated. All 33 cases of mesothelioma and all 20 cases of pulmonary adenocarcinoma with interpretable cores showed positive cytoplasmic staining. All but one case of mesothelioma and all pulmonary adenocarcinomas showed staining in at least 80% of the tumor cells. The mean H-score for glypican-1 of mesothelioma (134 ± 59, mean ± SD) was not significantly different from that for pulmonary adenocarcinoma (156 ± 60; P = 0.21). Neither epithelioid type (mean H-score 135 ± 57) nor sarcomatoid type (mean H-score 130 ± 78) of mesothelioma showed different H-scores when compared to pulmonary adenocarcinoma (P = 0.23 and 0.42, respectively). In conclusion, glypican-1 IHC does not differentiate mesothelioma from pulmonary adenocarcinoma.

In plain English

This laboratory study from Vancouver General Hospital in Canada tested whether a tissue stain for a protein called glypican-1 could help pathologists tell pleural mesothelioma apart from pulmonary (lung) adenocarcinoma. These two cancers can look alike under the microscope, and another research group had recently proposed glypican-1 as a marker for epithelioid mesothelioma. The authors stained small tissue samples from 33 mesotheliomas (28 epithelioid and five sarcomatoid), 21 pulmonary adenocarcinomas and 19 benign reactive mesothelial proliferations. One adenocarcinoma could not be assessed. Every mesothelioma and every assessable adenocarcinoma stained positive. All but one mesothelioma, and every adenocarcinoma, stained in at least 80% of tumor cells. The average staining score (H-score) was 134 for mesothelioma and 156 for adenocarcinoma, a difference that was not statistically significant (P = 0.21). Neither epithelioid nor sarcomatoid mesothelioma differed significantly from adenocarcinoma. The study did not examine asbestos exposure. The authors concluded that glypican-1 staining, in their hands, does not differentiate mesothelioma from pulmonary adenocarcinoma. They noted that their results differ from the earlier report.

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 (pathology) study testing a diagnostic tissue stain (glypican-1 immunohistochemistry) on tissue microarrays from archived surgical cases
• Who was studied: Archived tissue from 33 mesotheliomas (28 epithelioid, five sarcomatoid), 21 pulmonary adenocarcinomas (one later excluded) and 19 benign reactive mesothelial proliferations, from the surgical pathology files at Vancouver General Hospital, Canada; dates not given
• Exposure: No asbestos exposure was studied. What was tested was the glypican-1 immunohistochemical stain, using the same antibody and dilution as an earlier study.
• Main results:
  • All cases of mesothelioma, all assessable pulmonary adenocarcinomas (20 of 21; one excluded for insufficient tumor) and all benign reactive mesothelial proliferations showed positive cytoplasmic staining for glypican-1
  • All but one mesothelioma, and all pulmonary adenocarcinomas, showed staining in at least 80% of tumor cells
  • Mean H-score was 134 (standard deviation 59) for mesothelioma and 156 (standard deviation 60) for pulmonary adenocarcinoma; the difference was not statistically significant (P = 0.21)
  • Epithelioid mesothelioma (28 cases, mean H-score 135, standard deviation 57) and sarcomatoid mesothelioma (5 cases, mean H-score 130, standard deviation 78) did not differ significantly from pulmonary adenocarcinoma (P = 0.23 and 0.42)
  • Most mesotheliomas, 20 (61%), stained weakly; the most common intensity in pulmonary adenocarcinoma was moderate, in 10 (50%) cases
  • Benign reactive mesothelial proliferation had a lower mean H-score (119) than pulmonary adenocarcinoma (P = 0.03) but did not differ significantly from mesothelioma (P = 0.31); the authors said this difference is not helpful diagnostically
  • Median H-scores were 100 for mesothelioma, 170 for pulmonary adenocarcinoma and 100 for benign mesothelial proliferation
• The authors' conclusion: The authors concluded that glypican-1 immunohistochemistry, in their hands, does not differentiate mesothelioma from pulmonary adenocarcinoma, and that a stain highly sensitive and specific for mesothelioma remains desirable
• Limitations the authors state:
  • The authors used tissue microarrays rather than the whole tissue sections used in the earlier study, though they considered tumor heterogeneity unlikely to explain the different results
  • The authors stated that the reason their results disagree with the earlier study is unclear

Topics

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

Medical terms in this study, explained in our Lexicon: Immunohistochemistry, Mesothelioma, Adenocarcinoma, Pleural Mesothelioma, Cytology, Pleural Effusion, Epithelioid, Sarcomatoid.

Related studies

• Glypican-1 immunohistochemistry is a novel marker to differentiate epithelioid mesothelioma from lung adenocarcinoma — V.J. Amatya, K. Kushitani, et al. (2018)
• Monoclonal Caveolin 1 Expression in the Differential Diagnosis of Malignant Pleural Mesothelioma and Pulmonary Adenocarcinoma: Is it Useful? — Z. Bozdag, E. Tutar, et al. (2020)
• Utility of Claudin-4 versus BerEP4 and B72.3 in pleural fluids with metastatic lung adenocarcinoma — A. Patel, A.C. Borczuk, et al. (2020)
• Diffuse intrapulmonary mesothelioma mimicking pulmonary lepidic adenocarcinoma: a rare case report and review of the literature — W. RanYue, W. ChunYan, et al. (2023)
• Immunohistochemistry in the distinction between malignant mesothelioma and pulmonary adenocarcinoma: a critical evaluation of new antibodies — A.S. Abutaily, B.J. Addis, et al. (2002)
• BAP1 immunohistochemistry and p16 FISH to separate benign from malignant mesothelial proliferations — B.S. Sheffield, H.C. Hwang, et al. (2015)

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