SMARCB1/INI1/BAF47- deficient pleural malignant mesothelioma with rhabdoid features

Our plain-English summary of SMARCB1/INI1/BAF47- deficient pleural malignant mesothelioma with rhabdoid features, by N. Kimura, M. Hasegawa, K. Hiroshima (Pathology International, 2018).

The study

• Authors: N. Kimura, M. Hasegawa, K. Hiroshima
• Journal: Pathology International
• Published: 2018;68(2):128-132
• Type of article: Case report
• Cited by: 11 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Malignant mesothelioma (MM) with rhabdoid features is an MM variant. Fifteen cases have been reported previously, all of which were combined with other types of MM. Herein, we report an autopsy case of pleural MM with monomorphic rhabdoid features. The patient was a 62-year-old male without a history of asbestos exposure. An autopsy revealed a soft, granular tumor that replaced the entire left pleura and had invaded to the diaphragm and lower lobe of the lung. The tumor cells, which had eosinophilic plump cytoplasm and eccentric nuclei, were loosely cohesive. Immunohistochemistry showed that the cells were diffusely positive for calretinin, D2-40, vimentin, CAM5.2, and AE1/AE3; and negative for WT-1, TTF-1, CK7, CEA, desmin, CD34, BCL-2, S100 protein, and p40. Neither homozygous deletion of p16 nor BAP-1 protein loss was observed. Loss of INI1/BAF47 protein, an indicator of malignant rhabdoid tumor, was observed. Therefore, MM with rhabdoid features was confirmed.

© 2018 Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.

In plain English

This case report from Japan described one patient: a 62-year-old man with no history of asbestos exposure, referred with chest pain and an abnormal chest X-ray. He had a large build-up of fluid in the left chest and died eight months after admission. At autopsy, multiple soft nodular tumors filled the left pleural cavity, replaced the left pleura and diaphragm, and invaded the lower lobe of the left lung. No other organs were involved. Under the microscope the tumor showed loosely attached cells resembling a rhabdoid tumor. There were no structures typical of ordinary epithelioid or sarcomatoid mesothelioma. Stains were strongly positive for vimentin, D2-40 and BAP-1, focally positive for calretinin, CAM5.2 and AE1/AE3, and showed loss of SMARCB1/INI1/BAF47 protein. A p16 gene test (FISH) found no homozygous deletion. The authors diagnosed malignant pleural mesothelioma with rhabdoid features rather than a malignant rhabdoid tumor outside the kidney. They called this the first report of monomorphic mesothelioma with rhabdoid features and said more cases need to be collected and analyzed.

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 autopsy case)
• Who was studied: One 62-year-old man treated at National Hospital Organization Hakodate Hospital, Japan, who was examined at autopsy after death
• Exposure: No asbestos exposure reported: the patient had no history of asbestos exposure
• Main results:
  • The patient died eight months after admission
  • At autopsy the tumor involved the left pleural cavity, pleura, diaphragm and left lower lung lobe. There was no invasion of or spread to other organs, and 1350 mL of bloody pleural effusion had collected on the left side
  • No glandular or fibrous structures of ordinary epithelioid or sarcomatoid mesothelioma were seen in the tumor
  • The tumor cells were diffusely and strongly positive for vimentin, D2-40 and BAP-1, and focally but strongly positive for calretinin, CAM5.2 and AE1/AE3
  • The tumor cells had lost nuclear staining for SMARCB1/INI1/BAF47
  • In p16 FISH, 75% of tumor cells had a normal pattern and 18% a hemizygous deletion pattern. The authors concluded there was no homozygous deletion of p16 (their cut-off was more than 14.4% of nuclei)
• The authors' conclusion: The authors diagnosed the case as malignant mesothelioma with rhabdoid features rather than extra-renal malignant rhabdoid tumor, because the tumor spread along the pleura and mesothelial markers were positive. They described it as the first report of monomorphic mesothelioma with rhabdoid features.
• Limitations the authors state:
  • The authors stated that more such cases need to be collected with detailed data and analyzed in the future

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: Malignant Mesothelioma, Rhabdoid, Autopsy, Asbestos Exposure, Pleura, Diaphragm, Eosinophilic, Immunohistochemistry.

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• Mesothelioma with rhabdoid features: an ultrastructural and immunohistochemical study of 10 cases — N.G. Ordóñez (2006)
• Concurrent occurrence of renal cell carcinoma with rhabdoid features in a married couple: a case report — R. Matsumoto, N. Shinohara, et al. (2015)
• The diagnostic utility of reduced immunohistochemical expression of SMARCB1 in synovial sarcomas: a validation study — J. Ito, N. Asano, et al. (2016)
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