Diffuse pleural thickening and thoracic contraction: An indistinguishable case from malignant pleural mesothelioma

Our plain-English summary of Diffuse pleural thickening and thoracic contraction: An indistinguishable case from malignant pleural mesothelioma, by Y. Tada, M. Tagawa, T. Yusa, et al (SAGE Open Medical Case Reports, 2020).

The study

• Authors: Y. Tada, M. Tagawa, T. Yusa, M. Yatomi, I. Shimomura, T. Suzuki, Y. Takeshita, T. Sato, H. Shimada, K. Hiroshima
• Journal: SAGE Open Medical Case Reports
• Published: 2020;8:2050313X20948716
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

The differential diagnosis of reactive mesothelial hyperplasia and mesothelioma is difficult. We present a rare case of diffuse pleural thickening with thoracic contraction that was indistinguishable from mesothelioma. A 66-year-old woman with no history of asbestos exposure visited our hospital with a complaint of dyspnea. The clinical findings included circumferential pleural thickening on chest computed tomography image and a high concentration of hyaluronic acid in the pleural fluid. Pleural biopsies obtained by thoracoscopy under local anesthesia were pathologically consistent with mesothelioma, but the patient refused to take any kind of mesothelioma treatments. Four months later, she consented to a surgical pleural biopsy under general anesthesia to obtain larger tissue samples, which included typical proliferating polygonal cells positive for CAM5.2, calretinin, WT-1, D2-40, CK5/6, epithelial membrane antigen, and glucose transporter-1 and negative for carcinoembryonic antigen, BerEP4, and MOC31. The analysis was consistent with diagnosis of epithelioid mesothelioma. Fluorescence in situ hybridization, however, showed the presence of p16 gene, and the expression of BRCA1-associated protein-1 was detected by immunohistochemistry. Our final diagnosis was diffuse pleural thickening unrelated to asbestos exposure. Differential diagnosis of diffuse pleural thickening and malignant mesothelioma is thus difficult and routine immunohistochemical examinations are often insufficient for accurate diagnosis. Multiple diagnostic methods are required for correct diagnosis in a clinically marginal case.

© The Author(s) 2020.

In plain English

This case report described a 66-year-old Japanese woman, a housewife and non-smoker. She had no asbestos exposure, her residential area was not contaminated, and her family had not worked with asbestos. She had chest dullness; CT showed left-sided pleural thickening of 13 mm with fluid. The fluid had a high hyaluronic acid level (2,030,000 ng/mL). A first, small thoracoscopic biopsy under local anesthesia was diagnosed as epithelioid malignant pleural mesothelioma. She refused treatment. Four months later a larger surgical biopsy was taken. Routine immunostaining again matched mesothelioma. But the abnormal cells had not invaded beyond the pleura, a genetic test (FISH) did not show deletion of both copies of p16, and the cells expressed BAP1. This biopsy was diagnosed as fibrous pleuritis with reactive mesothelial hyperplasia; the authors' final diagnosis was diffuse pleural thickening unrelated to asbestos exposure. At a Japanese expert panel, 80% of pathologists had regarded the case as mesothelioma. She survived more than 11 years after fluid first appeared. The authors concluded that large open-surgery biopsies, p16 FISH and BAP1 testing are crucial for distinguishing mesothelioma from benign 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: case report (single patient)
• Who was studied: One 66-year-old Japanese woman, a housewife with no smoking history, referred to Chiba University Hospital, Japan
• Exposure: No asbestos exposure: she had never been exposed, her residential area was not contaminated, and her family had not worked with asbestos. The authors judged household or environmental exposure quite unlikely.
• Main results:
  • On admission, chest CT showed left-sided pleural thickening of 13 mm at the lower thorax with some pleural effusion.
  • The pleural fluid had an abnormally high hyaluronic acid concentration of 2,030,000 ng/mL.
  • The first biopsy, taken by video-assisted thoracoscopic surgery under local anesthesia, was diagnosed as epithelioid malignant pleural mesothelioma.
  • A PET scan showed no FDG uptake in the 4 cm nodule seen four months after the first biopsy.
  • In the surgical biopsy, FISH analysis of 100 atypical polygonal and spindle cells did not show homozygous deletion (deletion of both copies) of the p16 gene, and the cells were positive for BAP1.
  • The pathological diagnosis from the surgical biopsy was fibrous pleuritis with reactive mesothelial hyperplasia.
  • The authors' final diagnosis was diffuse pleural thickening unrelated to asbestos exposure.
  • At the Japan Mesothelioma Panel Meeting, 9 of 15 pathologists diagnosed epithelial pleural mesothelioma, and 3 others called it atypical mesothelial proliferation favoring mesothelioma. Overall, 80% of the pathologists regarded the case as mesothelioma.
  • The patient survived 3 years after the last biopsy without respiratory symptoms, and more than 11 years from the first appearance of pleural effusion.
• The authors' conclusion: The authors presumed that large open-surgery biopsy samples, p16 FISH analysis and BAP1 immunohistochemistry are crucial for distinguishing mesothelioma from benign diseases, in order to avoid misdiagnosis leading to highly invasive interventions.

Topics

Medical terms in this study, explained in our Lexicon: Diffuse Pleural Thickening, Pleural Mesothelioma, Differential Diagnosis, Reactive Mesothelial Hyperplasia, Mesothelioma, Asbestos Exposure, Dyspnea, Pleural Thickening.

Related studies

• Computer-assisted diagnosis for early stage pleural mesothelioma: towards automated detection and quantitative assessment of pleural thickening from thoracic CT images — K. Chaisaowong, T. Aach, et al. (2007)
• Asbestosis, pleural plaques and diffuse pleural thickening: three distinct benign responses to asbestos exposure — P.A. Gevenois, V. de Maertelaer, et al. (1998)
• Diffuse pleural thickening in asbestos workers: disability and lung function abnormalities — C.R. McGavin, G. Sheers (1984)
• Causes of pulmonary impairment in asbestos-exposed individuals with diffuse pleural thickening — S.T. Kee, G. Gamsu, et al. (1996)
• Clinical consequences of asbestos-related diffuse pleural thickening: A review — S.E. Miles, A. Sandrini, et al. (2008)
• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, et al. (1990)

Browse return to medical research.