Putative Malignant Pleural Mesothelioma in situ (MPMIS) with Sequential Acquisition of Genomic Alterations on Fluorescence in situ Hybridization (FISH) Examination

Our plain-English summary of Putative Malignant Pleural Mesothelioma in situ (MPMIS) with Sequential Acquisition of Genomic Alterations on Fluorescence in situ Hybridization (FISH) Examination, by S. Haefliger, S. Savice Prince, J. Rebetez, et al (Acta Cytologica, 2021).

The study

• Authors: S. Haefliger, S. Savice Prince, J. Rebetez, H. Borer, L. Bubendorf
• Journal: Acta Cytologica
• Published: 2021;65(1):99-104
• Type of article: Case report
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is a rare and deadly disease. A precursor in situ lesion, malignant pleural mesothelioma in situ (MPMIS), has recently been proposed. On cytological examination, the distinction between reactive and malignant mesothelial cells is often challenging, and sometimes even impossible without ancillary methods. Fluorescence in situ hybridization (FISH) for detection of 9p21 deletion is a powerful diagnostic tool in this context, both in histological and in cytological specimens. Here, we present a case of MPM with initial presentation as a putative MPMIS with disomic chromosomal pattern and homozygous 9p21 deletion with subsequent development of an aneuploid pattern after whole genome duplication during tumor progression.

© 2020 The Author(s). Published by S. Karger AG, Basel.

In plain English

This case report, from the University Hospital of Basel, Switzerland, also included a small review of stored samples. A 57-year-old non-smoking electro-mechanic was suspected of having malignant pleural mesothelioma. Fluid from around his lung showed cancerous mesothelial cells with extra copies of chromosomes 3, 7 and 17 and loss of both copies of a region called 9p21. A biopsy confirmed mesothelioma. Eight months earlier, his fluid and biopsy had been diagnosed as non-cancerous inflammation. Retesting those earlier samples showed loss of BAP1 and desmin and the same 9p21 loss, but no extra chromosome copies. The authors hypothesized that the earlier lesion could be an early, surface-only ('in situ') mesothelioma. Because sampling was limited, they could not rule out a missed invasive tumor. Among 60 mesothelioma and 60 reactive fluid samples reviewed, lymphocytes encircling mesothelial cells appeared in 5 (2 malignant, 3 reactive). The authors suggested such testing as a possible screening tool for people with asbestos exposure and unexplained effusions. The article does not report this patient's exposure.

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 of one patient, with a small retrospective review of archived pleural effusion cytology samples
• Who was studied: One 57-year-old man, a non-smoker working as an electro-mechanic, seen at the University Hospital of Basel, Switzerland. The review covered 60 effusion samples from proven malignant pleural mesothelioma and 60 reactive (non-cancerous) lymphocyte-rich effusions.
• Exposure: No asbestos exposure is reported for this patient; only his occupation (electro-mechanic) is given. Asbestos exposure is mentioned only in the authors' conclusion, about who might be screened.
• Main results:
  • At the time of clinically suspected mesothelioma, effusion cells showed unbalanced polysomy (extra copies) of chromosomes 3, 7 and 17 and homozygous loss of 9p21. A subsequent pleural biopsy confirmed malignant pleural mesothelioma.
  • Pleural fluid and a biopsy taken 8 months earlier had been diagnosed as unspecific organizing pleuritis without signs of malignancy, and no mesothelioma was suspected then.
  • Retrospective testing of the earlier samples showed loss of desmin and BAP1 expression and a homozygous 9p21 deletion, but no polysomy of chromosomes 3, 7 and 17.
  • The authors hypothesized that the tumor cells underwent whole genome duplication during the 8-month interval between the two samples.
  • In a review of 60 mesothelioma and 60 reactive effusion samples, satellitosis (lymphocytes encircling mesothelial cells) was seen in 5 cases in total: 2 with malignant mesothelial cells, including this patient, and 3 with reactive mesothelial cells.
• The authors' conclusion: The authors concluded that the case illustrates the potential usefulness of FISH and/or BAP1 testing as screening tools for malignant pleural mesothelioma in situ in patients at risk because of a history of asbestos exposure who have otherwise unexplained pleural effusion. They also concluded that satellitosis is rare and not tumor-specific.
• Limitations the authors state:
  • Because sampling was limited, the authors could not exclude an undetected focus of established mesothelioma at the time of the first effusion.
  • No tissue was left to test MTAP in the early samples.
  • Satellitosis might be only a physical artifact of sample processing.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Fluorescence In Situ Hybridization (FISH), Mesothelial Cells.

Related studies

• Fluorescence in situ hybridization (FISH) provides estimates of minute and interstitial BAP1, CDKN2A, and NF2 gene deletions in peritoneal mesothelioma — S. Brich, F. Bozzi, et al. (2020)
• Fluorescence in situ hybridization in the definitive diagnosis of malignant mesothelioma in effusion cytology — S. Savic, N. Franco, et al. (2010)
• Usefulness of p16/CDKN2A fluorescence in situ hybridization and BAP1 immunohistochemistry for the diagnosis of biphasic mesothelioma — D. Wu, K. Hiroshima, et al. (2017)
• Common Fluorescence In Situ Hybridization Applications in Cytology — S. Savic, L. Bubendorf (2016)
• Peritoneal malignant mesothelioma (PMM), and primary peritoneal serous carcinoma (PPSC) and reactive mesothelial hyperplasia (RMH) of the peritoneum. Immunohistochemical and fluorescence in situ hybridisation (FISH) analyses — T. Kawai, S. Tominaga, et al. (2016)
• MTAP immunohistochemistry is an accurate and reproducible surrogate for CDKN2A fluorescence in situ hybridization in diagnosis of malignant pleural mesothelioma — D.B. Chapel, J.J. Schulte, et al. (2020)

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