A case of slowly progressive malignant pericardial mesothelioma suggesting the involvement of BAP1 loss

Our plain-English summary of A case of slowly progressive malignant pericardial mesothelioma suggesting the involvement of BAP1 loss, by N. Fukasawa, Y. Agemi, A. Shiba, et al (Respirology Case Reports, 2022).

The study

• Authors: N. Fukasawa, Y. Agemi, A. Shiba, M. Aga, Y. Hamakawa, K. Miyazaki, Y. Taniguchi, Y. Misumi, T. Shimokawa, K. Ono, H. Hayashi, H. Okamoto
• Journal: Respirology Case Reports
• Published: 2022;10(9):e01004
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pericardial mesothelioma (MPM) is a rare tumour that arises from the mesothelial cells of the pericardium. No standard treatment has been established owing to a poor treatment response; therefore, MPM has a poor prognosis. We herein report a rare case of MPM in a 70-year-old man that was diagnosed immunohistopathologically using cell block sections of pericardial fluid and in which long-term survival for more than 3 years was achieved with only periodic pericardial drainage. Immunohistopathological staining investigations, especially BRCA1-associated protein 1 (BAP1) immunostaining using cell block sections of pericardial effusion, are effective in making a diagnosis of MPM. Well-differentiated papillary mesothelioma (WDPM) with BAP1 loss progresses to MPM in the long term, showing that BAP1 loss may induce phenotypical evolution of WDPM. BAP1 loss may also progress to malignant mesothelioma in situ and then to invasive mesothelioma. BAP1 immunohistochemistry should be considered for the early diagnosis of MPM.

© 2022 The Authors. Respirology Case Reports published by John Wiley & Sons Australia, Ltd on behalf of The Asian Pacific Society of Respirology.

In plain English

This case report described a 70-year-old man in Japan with malignant pericardial mesothelioma, a cancer of the lining around the heart. He had smoked 1 pack a day for 25 years. He had also worked at a press shop for 3 years from age 15, where, the authors wrote, he may have had low-level exposure to asbestos. No fiber type was named. Fluid repeatedly built up around his heart and was drained every 3 months for 2 years. Cytology of the fluid was not conclusive. However, stained sections made from the fluid showed mesothelial markers and loss of the protein BAP1, and this led to the diagnosis. Chemotherapy was difficult because of dementia, so drainage continued, and he remained alive without disease progression for 3 years. The authors called this slow course atypical and said well-differentiated papillary mesothelioma or mesothelioma in situ should therefore be considered. Because a biopsy was difficult, they added, it may not be possible to tell whether this was invasive mesothelioma or mesothelioma in situ. They concluded that BAP1 staining should be used more readily in recurrent pericardial effusion for earlier diagnosis.

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
• Who was studied: One 70-year-old man with atrial fibrillation, chronic kidney disease, chronic heart failure and hypertension, seen at the Department of Respiratory Medicine, Yokohama Municipal Citizen's Hospital, Japan; he had smoked 1 pack per day for 25 years until age 45
• Exposure: Work at a press shop for 3 years from age 15, with possible low-level asbestos exposure; no fiber type, product or dose given
• Main results:
  • Cytology of the pericardial fluid at the previous doctor showed class IIIb and did not reveal the cause of the effusion
  • At admission, more than 2000 ml of pericardial effusion was drained
  • The hyaluronic acid level in the pericardial fluid was 329,000 ng/ml, and cytology indicated class III
  • On cell block sections, tumour cells were diffusely positive for calretinin, D2-40 and WT-1, focally positive for EMA, negative for CEA, TTF-1 and desmin, and showed BAP1 loss
  • BAP1 loss was observed in the tumour cells
  • The staining led to a pathological diagnosis of pericardial mesothelioma
  • Systemic chemotherapy was difficult because of dementia; with pericardial drainage every 3 months, the patient remained alive with no disease progression for 3 years
• The authors' conclusion: The authors concluded that finding BAP1 loss is useful in diagnosis, and that the threshold for BAP1 immunostaining should be lowered in cases of recurrent pericardial effusion for early diagnosis of malignant pericardial mesothelioma
• Limitations the authors state:
  • Because pericardial biopsy was difficult, the authors said it may not be possible to distinguish this case between invasive mesothelioma and malignant mesothelioma in situ (MMIS)
  • Because surviving over 3 years without chemotherapy is atypical for malignant pericardial mesothelioma, the authors said well-differentiated papillary mesothelioma (WDPM) or MMIS should be considered in the differential diagnosis

Topics

Medical terms in this study, explained in our Lexicon: Pericardial Mesothelioma, BAP1, Mesothelial Cells, Pericardium, Prognosis, Cell Block, Pericardial, Pericardial Effusion.

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