Localized malignant mesothelioma of the pleura

Our plain-English summary of Localized malignant mesothelioma of the pleura, by H. Okamura, T. Kamei, A. Mitsuno, et al (Pathology International, 2001).

The study

• Authors: H. Okamura, T. Kamei, A. Mitsuno, H. Hongo, N. Sakuma, T. Ishihara
• Journal: Pathology International
• Published: 2001;51(8):654-60
• Type of article: Case report
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We describe a case of malignant pleural mesothelioma appearing as a solitary pleural tumor in a 56-year-old Japanese man with no history of exposure to asbestos. A chest radiograph revealed an isolated extrapulmonary mass in the left hemithorax. The patient underwent tumor resection, but the tumor later recurred on the contralateral pleura. The patient developed cerebral metastases and died 16 months after the initial surgery. The resected tumor was sessile with broad-based pleural attachment. Microscopically, the tumor was composed of interlacing fascicles of plump spindle cells intermixed with few polygonal cells. Most of the tumor cells showed positive immunoreactivity for cytokeratins (AE1 and AE3) and vimentin. Many of the tumor cells were positive for epithelial membrane antigen, and a few were positive for desmin. In contrast, the tumor cells were consistently negative for carcinoembryonic antigen, epithelial antigen BerEP4, calretinin, S-100 protein, neuron-specific enolase, muscle actin antigen HHF35, alpha-smooth muscle actin antigen and CD34. Ultrastructurally, the tumor cells had diffusely distributed cytoplasmic intermediate filaments, desmosome-like junctions, and a few microvilli. Some tumor cells contained cytoplasmic tonofilaments. Immunohistochemical and ultrastructural findings supported the mesothelial nature of the tumor, and led us to diagnose this tumor as a sarcomatoid localized malignant mesothelioma.

In plain English

This case report described one 56-year-old Japanese man whose malignant mesothelioma of the pleura appeared as a single, localized mass. He had no known history of occupational exposure to asbestos. Imaging showed an isolated pleura-based mass in the upper left chest involving the chest wall. Surgeons removed it with part of the lung and chest wall. Follow-up X-rays four months later showed a nearly identical mass on the opposite side, which the authors presumed was a recurrence. Sixteen months after surgery the cancer was found to have spread to the brain, and he died within a month. No autopsy was done. Under the microscope the tumor was made mostly of spindle-shaped cells and had invaded the chest wall and lung. The tumor cells stained for cytokeratin, EMA, vimentin and desmin, but not for markers including CD34 and calretinin. Electron microscopy showed desmosome-like junctions, tonofilament-like bundles and a few microvilli. The authors concluded the tumor was a sarcomatoid malignant mesothelioma, and that an isolated pleural tumor can, extremely rarely, be a malignant mesothelioma. They could not rule out microscopic disease elsewhere in the pleura.

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 report (single patient)
• Who was studied: One 56-year-old Japanese man treated at Yamaguchi Central Hospital, Hofu, Japan. He had 5 months of severe left posterior chest pain before admission. Dates of treatment are not given.
• Exposure: No asbestos exposure was studied. The article states the patient had no known history of occupational exposure to asbestos.
• Main results:
  • Before surgery, a chest X-ray showed an isolated pleura-based mass at the edge of the left upper lung.
  • Imaging found no other lung or abdominal masses and no pleural effusion.
  • The tumor was removed together with part of the lung and part of the chest wall.
  • Four months after surgery, a nearly identical pleura-based mass appeared on the opposite (contralateral) side.
  • Sixteen months after the first surgery, brain metastasis was found. The second pleural tumor had grown but stayed localized. The patient died within a month, and no autopsy was performed.
  • Tumor cells had invaded the soft tissues of the chest wall and the lung tissue.
  • On immunohistochemistry, tumor cells were positive for cytokeratin, EMA, vimentin and desmin (desmin in some cells). They were negative for the other antigens tested, including thrombomodulin, calretinin, NSE, S-100 protein and CD34.
  • Under electron microscopy, tumor cells had desmosome-like junctions, tonofilament-like bundles in the cytoplasm, and a few microvilli. There were no intercellular or intracellular lumina.
• The authors' conclusion: The authors regarded the tumor as a sarcomatoid malignant mesothelioma, based on these findings and the absence of another primary tumor. They concluded that an isolated pleural tumor can represent a malignant mesothelioma, although this is extremely rare.
• Limitations the authors state:
  • Because the tumor came back relatively soon after removal, the authors could not entirely exclude microscopic pleural disease away from the main tumor mass.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Localized Malignant Mesothelioma, Pleura, Pleural Mesothelioma, Chest X-Ray, Hemithorax, Contralateral Pleura, Spindle Cell, Epithelial Membrane Antigen (EMA).

Related studies

• Sarcomatous mesothelioma of the pleura with cerebral metastases — C. Nielsen, I.M. Hansen (1990)
• Localized fibrous tumours of the pleura: 15 new cases and review of the literature — M. Suter, S. Gebhard, et al. (1998)
• Localized fibrous tumors (LFTs) of the pleura: clinical data, asbestos burden, and syntactic structure analysis applied to newly defined angiogenic/growth-regulatory effectors — K. Kayser, J. Trott, et al. (2005)
• Benign localized fibrous tumor of the pleura: report of 25 new cases — S. Enon, D. Kilic, et al. (2012)
• Assessing Tumor-Infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method from the International Immuno-Oncology Biomarkers Working Group: Part 2: TILs in Melanoma, Gastrointestinal Tract Carcinomas, Non-Small Cell Lung Carcinoma and Mesothelioma, Endometrial and Ovarian Carcinomas, Squamous Cell Carcinoma of the Head and Neck, Genitourinary Carcinomas, and Primary Brain Tumors — S. Hendry, R. Salgado, et al. (2017)
• Localized fibrous "mesothelioma" of pleura (submesothelial fibroma): a clinicopathologic study of 18 cases — D. Scharifker, M. Kaneko (1979)

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