Diagnostic application of BAP1 immunohistochemistry to differentiate pleural mesothelioma from metastatic pleural tumours

Our plain-English summary of Diagnostic application of BAP1 immunohistochemistry to differentiate pleural mesothelioma from metastatic pleural tumours, by M. Yoshimura, Y. Kinoshita, M. Hamasaki, et al (Histopathology, 2017).

The study

• Authors: M. Yoshimura, Y. Kinoshita, M. Hamasaki, S. Matsumoto, T. Hida, Y. Oda, K. Nabeshima
• Journal: Histopathology
• Published: 2017;71(6):1011-1014
• Type of article: Letter
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Summary of the article

This letter reported a study of whether loss of BRCA-associated protein 1 (BAP1), detected by immunohistochemistry, could distinguish malignant pleural mesothelioma (MPM) from tumours that had spread to the pleura from elsewhere. The authors, from Fukuoka University and Kyushu University in Japan, first reviewed tumours that had metastasised to the pleura at their university hospital from 2000 to 2015. The most common primary tumours were lung carcinoma (9 cases), breast carcinoma (4) and signet ring cell carcinoma (3). They then stained 318 cases of MPM and of 10 tumour types that can metastasise to the pleura for BAP1. Staining could be assessed in 299 cases. BAP1 loss was found in 23 of 41 MPM cases (56%): 19 of 29 epithelioid cases (66%) and 2 of 6 cases each of biphasic and sarcomatoid MPM (33%). Among the other tumours, BAP1 loss occurred only in clear cell renal cell carcinoma (5 of 23, 22%). For separating MPM from metastatic tumours, BAP1 loss had a sensitivity of 56.1% and a specificity of 98.1%. Nineteen cases (6%) were excluded because of absent or faint staining of internal control cells or unclear staining of tumour cells. The authors concluded that, when properly assessed, BAP1 loss distinguishes MPM from most metastatic pleural tumours. They noted that clear cell renal cell carcinoma, intrahepatic cholangiocarcinoma and some melanocytic tumours can also show BAP1 loss.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This was a short research letter from pathologists in Fukuoka, Japan, about a laboratory stain for the BAP1 protein. The authors asked whether loss of BAP1 staining can tell malignant pleural mesothelioma apart from other cancers that spread to the pleura. The article does not discuss asbestos. A review of their university hospital's cases from 2000 to 2015 found that lung carcinoma was the most common cancer that had spread to the pleura (9 cases). The authors then stained samples of mesothelioma and of 10 tumor types that can spread to the pleura. 299 of 318 cases could be assessed. BAP1 loss was seen in 23 of 41 mesotheliomas (56%), including 19 of 29 epithelioid cases. Among the other tumors, only clear cell renal cell carcinoma showed loss, in 5 of 23. Overall sensitivity was 56.1% and specificity 98.1%. The authors concluded that, when properly assessed, BAP1 loss differentiates mesothelioma from metastatic pleural tumors. They noted exceptions, including clear cell renal cell carcinoma, and warned that staining artifacts can be misread as BAP1 loss.

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 (immunohistochemistry on tumor samples), published as a correspondence letter
• Who was studied: 318 tumor cases, 299 assessable: 41 malignant pleural mesotheliomas (29 epithelioid, 6 biphasic, 6 sarcomatoid) and 258 cases of 10 other tumor types that can spread to the pleura (lung, breast, stomach, esophagus, hypopharynx, thymus, kidney, ovary, bladder). Cases came from Fukuoka University Hospital and Kyushu University Hospital, Japan. Dates of the stained cases are not given. A separate review of pleural metastases at the authors' hospital covered 2000 to 2015.
• Exposure: Not an exposure study. Asbestos and fiber types are not mentioned. The factor studied was loss of BAP1 protein staining, tested with antibody clone C-4.
• Main results:
  • In the review of pleural metastases at the authors' hospital (2000 to 2015), the most common primary tumors were lung carcinoma (9 cases), breast carcinoma (4 cases) and signet ring cell carcinoma (3 cases).
  • In mesothelioma cases, BAP1 loss was found in 56% (23/41) overall. It was found in 66% (19/29) of epithelioid cases, and in 2 of 6 biphasic and 2 of 6 sarcomatoid cases.
  • No BAP1 loss was seen in any of the other tumor types except clear cell renal cell carcinoma.
  • In clear cell renal cell carcinoma, 22% (5/23) of tumors showed BAP1 loss.
  • Used to distinguish mesothelioma from the metastatic tumors, BAP1 loss had an overall sensitivity of 56.1% and specificity of 98.1%.
• The authors' conclusion: The authors concluded that, when assessed properly, BAP1 loss differentiates malignant pleural mesothelioma from metastatic pleural tumors, especially those from lung, breast and stomach. They noted that clear cell renal cell carcinoma, and tumors that other work reports can show BAP1 loss (intrahepatic cholangiocarcinoma, certain melanocytic tumors), must be kept in mind.
• Limitations the authors state:
  • 19 of 318 cases (6%) were excluded because control or tumor cell staining was absent, very faint, unclear or uneven.
  • BAP1 staining was lost in degenerated cells and in dividing cells. The authors warned that artifacts can be wrongly read as BAP1 loss, especially in small biopsies.

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: BAP1, Immunohistochemistry, Pleural Mesothelioma, Pleura, Carcinoma, Epithelioid, Biphasic Mesothelioma, Sarcomatoid.

Related studies

• BAP1 immunohistochemistry and p16 FISH results in combination provide higher confidence in malignant pleural mesothelioma diagnosis: ROC analysis of the two tests — T. Hida, M. Hamasaki, et al. (2016)
• A combination of MTAP and BAP1 immunohistochemistry is effective for distinguishing sarcomatoid mesothelioma from fibrous pleuritis — Y. Kinoshita, M. Hamasaki, et al. (2018)
• A combination of MTAP and BAP1 immunohistochemistry in pleural effusion cytology for the diagnosis of mesothelioma — Y. Kinoshita, T. Hida, et al. (2018)
• Highly expressed EZH2 in combination with BAP1 and MTAP loss, as detected by immunohistochemistry, is useful for differentiating malignant pleural mesothelioma from reactive mesothelial hyperplasia — M. Yoshimura, Y. Kinoshita, et al. (2019)
• The diagnostic role of BAP1 in serous effusions — B. Davidson, M. Tötsch, et al. (2018)
• Usefulness of p16/CDKN2A fluorescence in situ hybridization and BAP1 immunohistochemistry for the diagnosis of biphasic mesothelioma — D. Wu, K. Hiroshima, et al. (2017)

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