Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features

Our plain-English summary of Malignant pleural mesothelioma: clinicopathology of 16 extrapleural pneumonectomy patients with special reference to early stage features, by K. Hiroshima, T. Yusa, T. Kameya, et al (Pathology International, 2009).

The study

• Authors: K. Hiroshima, T. Yusa, T. Kameya, I. Ito, K. Kaneko, C. Kadoyama, H. Kishi, Y. Saitoh, D. Ozaki, M. Itami, T. Iwata, A. Iyoda, T. Kawai, I. Yoshino, Y. Nakatani
• Journal: Pathology International
• Published: 2009;59(8):537-45
• Type of article: Case report
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The earliest pathological events in the development of malignant pleural mesothelioma (MPM) are not understood. The aim of the present study was to elucidate the early histopathological features of MPM. A total of 16 extrapleural MPM pneumonectomy patients were investigated. Early stage mesothelioma was arbitrarily defined as a tumor < or =5 mm in thickness regardless of the nodal status or other organ involvement. Eight of these patients (six with epithelioid, two with biphasic) had early stage mesothelioma by this definition. Macroscopically there was no visible tumor, but the parietal and visceral pleura were thickened and there was focal adhesion between them. Microscopically, the mesothelioma lesions were multifocal and discontinuous on the pleura. In extremely early cases of epithelioid mesothelioma, tumor cells were generally arrayed in a single layer, but papillary proliferation was observed elsewhere. In sarcomatoid mesothelioma, mesothelioma cells proliferated, forming multiple small polypoid nodules on the pleura. Epithelial membrane antigen was helpful to distinguish reactive from neoplastic mesothelium, but glucose transporter-1 was not. Mesothelioma cells disseminate diffusely throughout the parietal and visceral pleura and mediastinal fat tissue before becoming visible. Stage Ia mesothelioma (neoplasm limited to the parietal pleura) would not be observed in daily practice.

In plain English

This Japanese study examined tissue from 16 men with malignant pleural mesothelioma who had extrapleural pneumonectomy (removal of one lung and its pleura) between 1995 and 2008. The authors set their own 'early stage' cutoff: a pleural tumor 5 mm thick or less, regardless of lymph-node or other organ involvement. Eight met it (six epithelioid, two biphasic); five of these were stage III by standard staging. The authors reported no tumor visible to the naked eye, though their table lists small nodules in some. Pleura were thickened and partly stuck together, and microscopic lesions were small, discontinuous and 1 to 5 mm thick. An epithelial membrane antigen (EMA) stain marked tumor in all 8 and nearby non-cancerous lining in 1 of 8. GLUT-1 marked tumor in 2 of 8. Three-year survival was 44% in early stage and 0% in the eight advanced cases (P = 0.0163). Nine patients were recorded as asbestos-exposed, but fiber types were not given. The authors concluded that tumor cells spread over both pleural layers before becoming visible. They also concluded that this surgery plus additional therapy prolongs survival in early stage disease.

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: Clinicopathological case series: microscopic and immunohistochemical study of whole surgical specimens, with survival comparison between early and advanced stage groups
• Who was studied: 16 patients with malignant pleural mesothelioma (all male in Table 1, aged 40 to 72) who underwent extrapleural pneumonectomy between 1995 and 2008 at the authors' institutes in Japan. 8 were classed as early stage and 8 as advanced stage.
• Exposure: Table 1 records asbestos exposure for each patient as present (9 patients), absent (4) or unknown (3). No fiber types, products, jobs or doses are given. Patients 4 and 8 are described as previously exposed to asbestos, and patient 4 had pleural plaque.
• Main results:
  • Early stage was defined as a pleural tumor 5 mm thick or less regardless of nodal status or other organ involvement. All other cases were defined as advanced stage.
  • Of the 8 early stage mesotheliomas, six were well differentiated epithelioid and two were biphasic. By IMIG stage, two were stage Ib, one stage II and five stage III.
  • The authors' text states there was no visible tumor to the naked eye in early stage mesothelioma, with thickened parietal pleura and focal adhesion between parietal and visceral pleura.
  • Table 2 lists small nodules as a macroscopic finding for some early stage patients. Patient 1 had small nodules on both pleurae, patient 2 had small nodules in the mediastinal pleura, and patient 6 had small nodules on the visceral pleura.
  • Microscopically, the early stage lesions were small and discontinuous, and the pleural tumor was 1 to 5 mm thick.
  • In the extremely early cases (patients 2 to 4), tumor cells were generally arranged in a single layer, with papillary growth elsewhere.
  • In the 8 early stage cases, EMA staining was positive in 8 of 8 mesotheliomas (100%) and in 1 of 8 areas of reactive mesothelium (13%). Desmin was positive in 1 of 8 mesotheliomas (13%) and 2 of 8 reactive areas (25%). GLUT-1 was positive in 2 of 8 mesotheliomas (25%) and 0 of 8 reactive areas.
  • The 8 early stage patients had 1, 2 and 3 year survival rates of 100%, 67% and 44%.
  • The 8 advanced stage patients had 1, 2 and 3 year survival rates of 57%, 14% and 0% (P = 0.0163 for the difference between groups).
• The authors' conclusion: The authors concluded that mesothelioma cells proliferate at many sites on both the parietal and visceral pleura before nodules become visible. They concluded that EMA was helpful but GLUT-1 was not a sensitive marker for early stage disease. Because T1a tumors are thought to progress to T1b immediately, they considered separating T1a from T1b not practical. They also concluded that extrapleural pneumonectomy with adjuvant therapy prolongs survival in early stage disease.
• Limitations the authors state:
  • The authors state that their definition of early stage mesothelioma was arbitrary.

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, Extrapleural Pneumonectomy (EPP), Pneumonectomy, Mesothelioma, Epithelioid, Biphasic Mesothelioma, Visceral Pleura, Pleura.

Related studies

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• Clinical and pathological features of three-year survivors of malignant pleural mesothelioma following extrapleural pneumonectomy — D.J. Sugarbaker, A.S. Wolf, et al. (2011)
• Is There a Role for Cancer-Directed Surgery in Early-Stage Sarcomatoid or Biphasic Mesothelioma? — S. Kim, D.A. Bull, et al. (2019)
• Staging of patients after extrapleural pneumonectomy for malignant pleural mesothelioma--institutional review and current update — C. Cao, S.K. Krog Andvik, et al. (2011)
• Laparoscopic repair of gastric herniation after extrapleural pneumonectomy for mesothelioma — M. Egan, B.E. Louie, et al. (2012)
• Pleurectomy/decortication is superior to extrapleural pneumonectomy in the multimodality management of patients with malignant pleural mesothelioma — L. Lang-Lazdunski, A. Bille, et al. (2012)

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