Diffuse malignant mesothelioma

Our plain-English summary of Diffuse malignant mesothelioma, by S.P. Oviedo, P.T. Cagle (Archives of Pathology & Laboratory Medicine, 2012).

The study

• Authors: S.P. Oviedo, P.T. Cagle
• Journal: Archives of Pathology & Laboratory Medicine
• Published: 2012;136(8):882-8
• Type of article: Case report, Review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Diffuse malignant mesothelioma (DMM) is an uncommon cancer with great clinical significance because it currently remains an incurable disease, and most patients die within months after diagnosis. Although DMM incidence is leveling off or decreasing in developed countries because of the strict control of asbestos use, it is increasing in countries without adequate asbestos control. In some settings, benign, reactive mesothelial hyperplasias and organizing pleuritis can be difficult to differentiate from DMM and vice versa, and the variety of DMM's histopathologic features generates an extensive list of differential diagnoses with other malignancies, particularly, metastatic malignancies, which are more frequent in the pleura than are primary malignancies. These two issues are the topic of discussion in this review, along with a brief presentation of a case of DMM that presented in a 66-year-old man with recurrent, right pleural effusions, and in whom, diagnosis of DMM had not been suspected clinically, radiographically, surgically, grossly, or initially, on frozen section. It was not until focal invasion into the skeletal muscle was discovered on permanent sections that a diagnosis of DMM could be established.

In plain English

This article was a review of why diffuse malignant mesothelioma (DMM) of the pleura can be hard to diagnose, opening with a brief report of one case. A 66-year-old man had recurrent fluid around the right lung. Tissue peeled from his right pleura and chest wall was first read on frozen section as fibrous pleural plaques with chronic inflammation. On permanent sections, mesothelial-type cells were found focally invading skeletal muscle, and DMM was diagnosed on that basis. It had not been suspected beforehand. The article did not say whether he had been exposed to asbestos. The review explained that benign reactive mesothelial growth can look malignant, sometimes more atypical than DMM, while invasion into underlying fat, muscle or lung is diagnostic of DMM. It noted that most pleural cancers are metastatic, with fewer than 2000 DMM cases per year in the United States. The authors recommended the term atypical mesothelial proliferation when a biopsy cannot settle benign versus malignant, and urged pathologists to consider cancers other than lung adenocarcinoma.

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: Narrative review of the pathologic diagnosis of diffuse malignant mesothelioma, with a brief case report
• Who was studied: One 66-year-old man with recurrent right pleural effusion (case report); the review itself did not study a group of patients
• Exposure: Not studied. No asbestos exposure is described for the patient. As background, the authors mention that most traditional cases are closely associated with occupational asbestos exposure.
• Main results:
  • In the case, the frozen-section diagnosis was fibrous pleural plaques with chronic inflammation.
  • On permanent sections, the patient's epithelioid cells were seen focally infiltrating skeletal muscle, and this led to the DMM diagnosis.
  • In the case, DMM could not be diagnosed until the focal invasion was found on permanent sections.
  • The review stated that some florid, reactive (benign) mesothelial hyperplasia can show greater cytologic atypia than some epithelioid DMM.
  • The review stated that invasion into underlying tissues (adipose tissue or skeletal muscle under the parietal pleura, lung under the visceral pleura) is diagnostic of DMM.
  • The review stated that most cancers involving the pleura are metastatic.
  • The review stated that DMM is uncommon, with fewer than 2000 cases per year in the United States.
  • The review stated that pathologists should consider primary sites other than the lungs, and cancer types other than adenocarcinoma, when separating DMM from other cancers.
• The authors' conclusion: The authors recommended the term atypical mesothelial proliferation when a specimen cannot be determined to be benign or malignant, for example at frozen section or on an inconclusive biopsy.
• Limitations the authors state:
  • The authors state that the immunostaining features of the full range of cancers that might spread to the pleura and mimic DMM are beyond the scope of this review.

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, Reactive Mesothelial Hyperplasia, Pleura, Pleural Effusion, Frozen Section.

Related studies

• Fibre distribution in the lungs and pleura of subjects with asbestos related diffuse pleural fibrosis — A.R. Gibbs, M. Stephens, et al. (1991)
• Open lung biopsy in patients with diffuse pulmonary shadowing — G.E. Venn, P.H. Kay, et al. (1985)
• Respiratory function changes after asbestos pleurisy — P.H. Wright, A. Hanson, et al. (1980)
• Outcome of patients with nonspecific pleuritis/fibrosis on thoracoscopic pleural biopsies — H.E. Davies, J.E. Nicholson, et al. (2010)
• Outcome of patients diagnosed with fibrinous pleuritis after medical thoracoscopy — M. Metintas, G. Ak, et al. (2012)
• Sonography of the pleura — J. Reuss (2010)

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