Unusual Histology in Mesothelioma: A Report of Two Cases with a Brief Review

Our plain-English summary of Unusual Histology in Mesothelioma: A Report of Two Cases with a Brief Review, by F. Bono, S. Ceola, C. Beretta, et al (Diagnostics, 2022).

The study

• Authors: F. Bono, S. Ceola, C. Beretta, M. Jaconi
• Journal: Diagnostics
• Published: 2022;12(2)
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Mesothelioma is often difficult to diagnose due to its rarity and its unusual histopathological features that could lend to diagnostic pitfalls and misdiagnosis. The WHO histological classification of pleural tumors in 2021 recommended a pathologic grading system for malignant pleural mesothelioma. Architectural aspects and cytological features, with nuclear grading, bent on a neoplastic score with fundamental prognostic and diagnostic value. Unusual features must be correctly assigned in the grading system to avoid misdiagnosis, especially toward metastatic lesions or reactive pleural processes. In this paper, we present two cases as examples of unusual morphological and architectural features with a brief literature review.

In plain English

This brief report from San Gerardo Hospital in Monza, Italy, described two patients with epithelioid pleural mesothelioma that looked unusual under the microscope, followed by a short review of the medical literature on diagnosing such tumors. The first patient, a 68-year-old man with possible asbestos exposure, had fluid around the right lung (pleural effusion). Biopsies showed tumor cells forming tubular and cystic spaces (the "adenomatoid" type), and the BAP1 protein was retained. He received cisplatin and pemetrexed chemotherapy and later surgery. The disease then spread to the other side of the chest, and he died of his disease. The second patient, a 53-year-old former smoker and railway worker with asbestos exposure, had tumor cells with a "signet ring" appearance and loss of BAP1. After chemotherapy, surgery and radiotherapy, he was alive with the disease under control at the time of writing, 18 months later. The article did not name asbestos fiber types. The authors concluded that, with supporting laboratory tests and awareness of rare variants, a correct diagnosis is possible.

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: Brief report of two cases (case reports) with a brief literature review
• Who was studied: Two male patients seen at San Gerardo Hospital, Monza, Italy: a 68-year-old man (case 1) and a 53-year-old male railway worker and former smoker (case 2). Dates of care are not given.
• Exposure: Asbestos: described as 'possible exposure' for case 1 and as 'exposure to asbestos' for case 2, a railway worker. No fiber type, product or dose was reported. Case 2 was also a former smoker.
• Main results:
  • Case 1: biopsy showed epithelioid tumor cells in tubular and cystic spaces with adenomatoid features, infiltrating the full thickness of the pleura with focal fat invasion. The tumor was diagnosed as epithelioid mesothelioma of the adenomatoid type.
  • Case 1: the tumor cells kept (retained) nuclear BAP1 staining.
  • Case 1: after chemotherapy and subtotal right pleurectomy, the disease progressed to the other side of the chest. The patient died two months after the later diagnosis on the left side.
  • Case 2: biopsy showed epithelioid cells growing in a diffuse pattern with vacuolated cytoplasm and a signet ring appearance (signet ring cell mesothelioma).
  • Case 2: the tumor cells were positive for mesothelial markers and had lost nuclear BAP1 staining.
  • Case 2: after chemotherapy, right pleural decortication and radiotherapy (45 Gy in 25 fractions), the patient was alive with the disease under control at the time of writing, 18 months later.
• The authors' conclusion: The authors concluded that the two cases are examples of diagnostic difficulties in epithelioid mesothelioma, and that with ancillary methods, and keeping rare histological variations in mind, a correct diagnosis is possible.

Topics

Medical terms in this study, explained in our Lexicon: Histology, Mesothelioma, Misdiagnosis, Histological Subtype, Pleural Mesothelioma, Nuclear Grading.

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• Shorter Survival in Malignant Pleural Mesothelioma Patients With High PD-L1 Expression Associated With Sarcomatoid or Biphasic Histology Subtype: A Series of 214 Cases From the Bio-MAPS Cohort — S. Brosseau, C. Danel, et al. (2019)

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