Bilateral Pleural Mesothelioma In Situ and Peritoneal Mesothelioma In Situ Associated With BAP1 Germline Mutation: A Case Report

Our plain-English summary of Bilateral Pleural Mesothelioma In Situ and Peritoneal Mesothelioma In Situ Associated With BAP1 Germline Mutation: A Case Report, by A. MacLean, A. Churg, S.T. Johnson (JTO Clinical and Research Reports, 2022).

The study

• Authors: A. MacLean, A. Churg, S.T. Johnson
• Journal: JTO Clinical and Research Reports
• Published: 2022;3(8):100356
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Mesothelioma in situ is a recently described precursor to invasive mesothelioma. Thus far, all cases in the literature have involved one pleural cavity or the peritoneal cavity. We describe a patient with biopsy-proven mesothelioma in situ involving both pleural cavities and the peritoneal cavity. Genetic analysis results revealed that the patient had a BAP1 germline mutation. This is the first report of mesothelioma in situ involving multiple body cavities and raises a question of whether such patients will all have BAP1 germline mutations.

© 2022 The Authors.

In plain English

This was a case report of one patient, a 43-year-old woman who had been diagnosed in 2015 with left breast cancer and had received chemotherapy and radiotherapy to the left side of the chest wall. There was no known history of asbestos exposure. In November 2019 the patient developed fluid around the right lung. A biopsy in March 2020 showed mesothelioma in situ, with no evidence of invasion. Mesothelioma in situ is an early, non-invasive form of mesothelioma recognised by loss of the BAP1 protein in the lining cells. A biopsy of the left pleura, which looked normal, showed the same picture. In October 2020, after a small bowel obstruction, biopsies of the abdominal lining showed peritoneal mesothelioma in situ, and no invasive mesothelioma was found. Genetic testing found a germline mutation in the BAP1 gene. The patient was started on nivolumab and ipilimumab, and follow-up scans showed no invasive disease. The authors concluded that BAP1 mutations can lead to mesothelioma in situ in multiple body cavities. They called it possible, but speculative, that the earlier radiation therapy provided a 'second hit' that triggered the disease.

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: case report (single patient)
• Who was studied: One patient, a 43-year-old woman diagnosed in 2015 with left breast invasive ductal carcinoma. The patient presented with a right pleural effusion in November 2019.
• Exposure: No known asbestos exposure. The patient had received adjuvant chemotherapy and radiotherapy to the left side of the chest wall for breast cancer, and carried a germline BAP1 mutation.
• Main results:
  • The right pleural biopsy (March 2020) showed mildly atypical mesothelial cells with nuclear loss of BAP1 staining and no invasion. Mesothelioma in situ was diagnosed.
  • The left pleura looked normal, but the biopsy showed a picture identical to the right side, with loss of BAP1. Mesothelioma in situ was diagnosed.
  • In October 2020, peritoneal biopsies showed a papillary and flat mesothelial proliferation with loss of BAP1, consistent with peritoneal mesothelioma in situ. No invasive mesothelioma was identified.
  • Genetic analysis found a germline two-base pair frameshift deletion in BAP1.
  • The patient was treated with nivolumab and ipilimumab. Follow-up chest CT and abdominal MRI showed no evidence of invasive disease.
• The authors' conclusion: The authors concluded that BAP1 mutations can lead to mesothelioma in situ in multiple serosal (body-lining) cavities.
• Limitations the authors state:
  • The authors described their idea that therapeutic radiation provided the 'second hit' as possible but speculative. They noted that it assumes enough radiation scatter reached both the other pleural cavity and the abdomen.

Topics

Medical terms in this study, explained in our Lexicon: Bilateral, Pleural Mesothelioma, Peritoneal Mesothelioma, BAP1, Germline Mutation, Mesothelioma in Situ, Mesothelioma, Pleural Cavity.

Related studies

• Detecting germline BAP1 mutations in patients with peritoneal mesothelioma: benefits to patient and family members — M. Kittaneh, C. Berkelhammer (2018)
• First case report of malignant peritoneal mesothelioma and oral verrucous carcinoma in a patient with a germline PTEN mutation: a combination of extremely rare diseases with probable further implications — M.W. Löffler, J. Steinhilber, et al. (2018)
• Germline BAP1 mutations predispose to malignant mesothelioma — J.R. Testa, M. Cheung, et al. (2011)
• Frequency of Germline Mutations in Cancer Susceptibility Genes in Malignant Mesothelioma — V. Panou, M. Gadiraju, et al. (2018)
• A Subset of Mesotheliomas With Improved Survival Occurring in Carriers of BAP1 and Other Germline Mutations — S. Pastorino, Y. Yoshikawa, et al. (2018)
• Germline mutation of Bap1 accelerates development of asbestos-induced malignant mesothelioma — J. Xu, Y. Kadariya, et al. (2014)

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