Sneaky Diagnosis of Pleural Malignant Mesothelioma in Thoracic Surgery: All That Glitters Is Not Gold

Our plain-English summary of Sneaky Diagnosis of Pleural Malignant Mesothelioma in Thoracic Surgery: All That Glitters Is Not Gold, by R. Orlandi, F. Bono, D.L. Cortinovis, et al (Journal of Clinical Medicine, 2022).

The study

• Authors: R. Orlandi, F. Bono, D.L. Cortinovis, G. Cardillo, U. Cioffi, A. Guttadauro, E. Pirondini, S. Canova, E.M. Cassina, F. Raveglia
• Journal: Journal of Clinical Medicine
• Published: 2022;11(11)
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant Pleural Mesothelioma (MPM) is a highly aggressive disease whose diagnosis could be challenging and confusing. It could occur with atypical presentations on every examined level. Here, we present three unconventional cases of the complex diagnostic process of MPM that we have experienced during routine practice: a patient with reactive mesothelial hyperplasia mimicking MPM, an unexpected presentation of MPM with persistent unilateral hydropneumothorax, a rare case of MPM in situ. Then, we review the relevant literature on each of these topics. Definitive biomarkers to confidently distinguish MPM from other pleural affections are still demanded. Patients presenting with persistent hydropneumothorax must always be investigated for MPM. MPM in situ is now a reality, and this raises questions about its management.

In plain English

This article from a thoracic surgery department in Monza, Italy, described three patients with unusual diagnostic courses involving malignant pleural mesothelioma (MPM) and reviewed published literature on each. A 49-year-old woman's pleural biopsies were first read as suggestive of epithelioid MPM, but a second pathologist concluded the changes were reactive; at two years she was alive without evidence of macroscopic disease. A 77-year-old woman without known asbestos exposure had air and fluid in the chest (hydropneumothorax) that drainage did not fully resolve; biopsies showed epithelioid MPM, and she died sixteen months after diagnosis. A 70-year-old farmer without known asbestos exposure was diagnosed with MPM in situ, with abnormal cells on the pleural surface but no invasion; at one year he remained free of macroscopic pleural disease. The authors concluded that definitive markers to separate MPM from other pleural conditions are still sought, that persistent unilateral hydropneumothorax should always be investigated for MPM, and that long-term follow-up of MPM in situ is needed. They noted its diagnosis rests on BAP1 loss, whose reliability is not full.

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 series of three patients with a review of the published literature on each case's topic
• Who was studied: Three patients seen at the authors' center, the Department of Thoracic Surgery, San Gerardo Hospital, Monza, Italy, in recent years: a 49-year-old woman, a 77-year-old woman, and a 70-year-old man. The center diagnoses on average 26 MPM cases per year.
• Exposure: Asbestos exposure was not studied. The 77-year-old woman (Case 2) and the 70-year-old man, a farmer (Case 3), are described as having no known exposure to asbestos. No asbestos history is reported for Case 1, and no fiber types are named.
• Main results:
  • Case 1 (49-year-old woman): pleural biopsies were initially interpreted as atypical proliferation suggestive of epithelioid MPM, without clear tissue invasion.
  • Case 1: FISH testing found p16 (9p21) homozygously deleted in 8% of the sample and heterozygously deleted in 67%.
  • Case 1: a second pathologist reviewed all pleural samples and concluded the changes were consistent with a reactive process. At the two-year radiological follow-up she was alive without evidence of macroscopic disease.
  • Case 2 (77-year-old woman presenting with right hydropneumothorax): pleural histology showed epithelioid MPM that was BAP1-negative.
  • Case 2: after chemotherapy the disease progressed locally, and she died sixteen months after diagnosis.
  • Case 3 (70-year-old man presenting with right pneumothorax): pleural sections showed a single layer of mesothelial cells with mild atypia and defective BAP1 expression, without invasion. With no radiologic or direct signs of neoplasia, MPM in situ was diagnosed.
  • Case 3: at the one-year CT scan he was still free from macroscopic pleural disease.
• The authors' conclusion: The authors concluded that: (1) definitive biomarkers to confidently distinguish MPM from other pleural conditions are still sought; (2) patients with persistent unilateral hydropneumothorax must always be investigated further for MPM, even without known asbestos exposure or smoking; (3) MPM in situ is now a reality, and long-term follow-up and management of it are required.
• Limitations the authors state:
  • The authors considered the concept of MPM in situ, as diagnosed in Case 3, still somewhat controversial, because its diagnosis rests only on BAP1 loss, whose reliability is not full.
  • The authors stated that one year of follow-up may be too short to tell very early MPM apart from reactive pleuritis.
  • For Case 1, the authors said the pleural nodules are hard to explain, and that often only close clinical follow-up can distinguish between these conditions.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Thoracic Surgery, Pleural Mesothelioma, Reactive Mesothelial Hyperplasia, Biomarker.

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