Mediastinal undifferentiated pleomorphic sarcoma with pleural effusion cytopathologically misdiagnosed as epithelial malignant pleural mesothelioma: An autopsy case report

Our plain-English summary of Mediastinal undifferentiated pleomorphic sarcoma with pleural effusion cytopathologically misdiagnosed as epithelial malignant pleural mesothelioma: An autopsy case report, by K. Matsumoto, Y. Nakamura, Y. Inagaki, et al (Thoracic Cancer, 2021).

The study

• Authors: K. Matsumoto, Y. Nakamura, Y. Inagaki, Y. Taniguchi, A. Tamiya, Y. Matsuda, T. Kasai, S. Atagi
• Journal: Thoracic Cancer
• Published: 2021;12(7):1137-1140
• Type of article: Case report
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Undifferentiated pleomorphic sarcoma (UPS) is a new disease in the World Health Organization's classification of tumors of soft tissue and bone published in 2013. Primary mediastinal UPS is rare, especially with pleural effusion. Herein, we describe the pathological findings of pleural effusion followed by mediastinal UPS, which was initially misdiagnosed as epithelial malignant pleural mesothelioma (MPM). The cytopathological findings of the pleural effusion cell block often contribute to the diagnosis of various malignant tumors. However, these findings may lead to misdiagnosis of highly invasive mediastinal tumors such as UPS. A biopsy for primary mediastinal lesions should be performed because MPM rarely mimics mediastinal tumors with pleural effusion.

© 2021 The Authors. Thoracic Cancer published by China Lung Oncology Group and John Wiley & Sons Australia, Ltd.

In plain English

This case report from a chest hospital in Osaka, Japan, described a 50-year-old man who had worked in construction with significant asbestos exposure since age 20 and had smoked two packs of cigarettes a day for 25 years. He came to hospital with sudden shortness of breath. Scans showed fluid around the right lung, two nodules on the pleura and a large tumor in the mediastinum, the central chest space, invading the sac around the heart. Cells from the drained fluid stained positive for mesothelial markers (calretinin, D2-40, WT-1, HEG1), so malignant pleural mesothelioma was suspected. A needle biopsy of the chest tumor looked completely different and was negative for almost all markers. He died a few days later of untreated cardiac tamponade, meaning compression of the heart. Autopsy found a 160 × 150 × 140 mm tumor, diagnosed as undifferentiated pleomorphic sarcoma, and few asbestos bodies. The tumor had invaded the pericardium and pleura, producing reactive mesothelial cells, and the authors wrote that mesothelioma was almost ruled out. The authors concluded that the mediastinal tumor itself should be biopsied.

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: autopsy case report (one patient)
• Who was studied: One 50-year-old man with acute onset of shortness of breath, referred to the National Hospital Organization Kinki-Chuo Chest Medical Center, Osaka, Japan; dates not given
• Exposure: Work in the construction industry with significant asbestos exposure since age 20 (fiber type not stated); also smoked two packs of cigarettes per day for 25 years
• Main results:
  • Chest CT showed moderate right pleural effusion, two pleural nodules and a large mediastinal tumor invading the pericardium
  • In the pleural fluid cell block, calretinin, D2-40, WT-1 and HEG1 were positive and TTF-1, CEA, claudin-4 and desmin were negative, so malignant pleural mesothelioma was suspected
  • A needle biopsy of the mediastinal tumor was negative for almost all markers, and its findings were completely different from those of the pleural fluid
  • The patient died a few days later of untreated cardiac tamponade
  • At autopsy the mediastinal tumor measured 160 × 150 × 140 mm, was negative for almost all markers, and was diagnosed as undifferentiated pleomorphic sarcoma (UPS)
  • The autopsy revealed few asbestos bodies; the tumor had invaded the mesothelium of the pericardium and pleura, producing reactive mesothelial cells, and the authors stated that mesothelioma was almost ruled out
• The authors' conclusion: The authors concluded that pleural fluid cell block findings may lead to misdiagnosis of highly invasive mediastinal tumors such as UPS, and that a biopsy of the primary mediastinal lesion should be performed

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleomorphic, Sarcoma, Pleural Effusion, Pleural Mesothelioma, Autopsy, Cell Block, Misdiagnosis, Biopsy.

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