Diagnostic Challenges in Epithelioid Pleural Mesothelioma: Case Series with Support from Electron Microscopy

Our plain-English summary of Diagnostic Challenges in Epithelioid Pleural Mesothelioma: Case Series with Support from Electron Microscopy, by F. Fortarezza, M. Della Barbera, F. Pezzuto, et al (Diagnostics, 2021).

The study

• Authors: F. Fortarezza, M. Della Barbera, F. Pezzuto, F. Lunardi, E. Faccioli, G. Pasello, F. Rea, S. Rizzo, F. Calabrese
• Journal: Diagnostics
• Published: 2021;11(5)
• Type of article: Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The histological diagnosis of pleural epithelioid mesothelioma can be difficult in the case of rare variants or in the definition of neoplasm origin in patients with previous or concomitant tumours. Currently, several immunohistochemical reactions are available in the surgical pathologist's armamentarium that allow us to obtain a more sensitive and specific diagnosis of malignant pleural mesothelioma. However, in some cases, the final interpretation remains inconclusive. Historically, ultrastructural examination has represented a useful tool for the definition of the mesothelial nature of neoplastic cells due to their peculiar morphological characteristics. The recent international guidelines for pathological diagnosis of pleural mesothelioma suggest the use of electron microscopy when the immunohistochemical reactions are equivocal or when further support of a diagnosis of mesothelioma is needed. This paper presents three cases of pleural epithelioid mesothelioma whose diagnoses were finally supported by ultrastructural examination.

In plain English

This article is a case series describing three patients with epithelioid pleural mesothelioma whose diagnosis was difficult and was finally supported by transmission electron microscopy. The first patient was a 72-year-old non-smoking man with occupational asbestos exposure. His tumour had areas that looked like squamous cells, and both parts of the tumour had lost nuclear BAP1 expression. Electron microscopy showed branched microvilli, supporting a diagnosis of epithelioid mesothelioma with areas of squamous metaplasia. The second patient was a 41-year-old man described as unexposed. He had a single pleural nodule found after a fall, which was diagnosed as localized malignant mesothelioma. The third patient was a 69-year-old woman described as unexposed, with earlier right breast cancer treated with chemo-radiotherapy. Her immunohistochemistry could not distinguish spread of breast cancer from a primary pleural tumour. Electron microscopy showed elongated, branched microvilli, and mesothelioma was diagnosed. The authors suggested a possible link between her earlier radiation and the tumour. They concluded that electron microscopy can help when immunohistochemistry is inconclusive or a case is very rare.

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 (three case reports) with a short literature discussion
• Who was studied: Three patients with pleural epithelioid mesothelioma: a 72-year-old man, a 41-year-old man and a 69-year-old woman; authors from the University of Padova, Italy; dates not given
• Exposure: Case 1 had occupational exposure to asbestos (fiber type not stated). Cases 2 and 3 were described as unexposed. Case 3 had prior chemo-radiotherapy for right breast cancer.
• Main results:
  • Case 1: both the mesothelial and squamous components of the tumour showed nuclear loss of BAP1 expression
  • Case 1: electron microscopy showed branched microvilli on most tumour cells, supporting a diagnosis of epithelioid mesothelioma with areas of squamous metaplasia
  • Case 2: a single pleural-based nodule was resected and diagnosed as localized malignant mesothelioma with deciduous changes
  • Case 3: immunohistochemistry on the biopsy could not decide between spread of breast cancer to the pleura and a primary pleural tumour; estrogen receptors were weakly positive in only 5% of tumour cells
  • Case 3: electron microscopy showed elongated, branched microvilli without glycocalyx and with tight junctions, and the diagnosis was malignant epithelioid mesothelioma of the pleura
  • Case 3: the authors noted the tumour arose at the same site as the earlier breast cancer radiotherapy and suggested a possible link
• The authors' conclusion: The authors concluded that ultrastructural (electron microscopy) analysis has contributory value when immunohistochemistry is inconclusive or when a case is very rare.
• Limitations the authors state:
  • In case 2, some details in the electron microscopy images were affected by non-optimal tissue preservation, although the authors state the structures needed for diagnosis appeared well preserved

Topics

Medical terms in this study, explained in our Lexicon: Epithelioid, Pleural Mesothelioma, Mesothelioma, Neoplasm.

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