Synovial sarcoma of the pleura and its differentiation from other primary pleural tumours: a clinicopathological and immunohistochemical review of three cases

Our plain-English summary of Synovial sarcoma of the pleura and its differentiation from other primary pleural tumours: a clinicopathological and immunohistochemical review of three cases, by A.G. Nicholson, P. Goldstraw, C. Fisher (Histopathology, 1998).

The study

• Authors: A.G. Nicholson, P. Goldstraw, C. Fisher
• Journal: Histopathology
• Published: 1998;33(6):508-13
• Type of article: Case report
• Cited by: 78 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims: Synovial sarcomas are rare tumours occasionally arising in the pleural cavity, a site where their histological characteristics may be mistaken for those of malignant mesothelioma. We examined three cases of primary pleural synovial sarcoma in order to look for clinicopathological features that may help in distinguishing them from both mesotheliomas and other sarcomas that may arise in the pleura.

Methods And Results: All three patients were male, aged 42, 28 and 42, respectively, and had no known exposure to asbestos. One biphasic tumour contained neutral mucin in focal epithelial elements that also stained positively for BerEP4 and AUA1. All three tumours showed focal positivity for either keratin or EMA in the sarcomatous elements, and they also stained positively for bcl-2 protein and MIC2 gene product (CD99).

Conclusions: Our results emphasize the importance of being aware of synovial sarcoma as a possible primary pleural malignancy, especially in a young patient with a localized mass. In addition, the presence of bcl-2 protein perhaps represents a useful marker in distinguishing synovial sarcoma, especially monophasic variants, from mesothelioma within a panel of antibodies.

In plain English

This article described three cases of synovial sarcoma, a rare soft-tissue cancer, arising in the pleura (the lining around the lungs). The authors found one case by reviewing all pleural malignant mesotheliomas diagnosed at the Royal Brompton Hospital, London, since 1990. A biopsy in that patient had suggested mesothelioma. All three were men, aged 42, 28 and 42, with no known asbestos exposure. Each tumour formed a localized mass rather than spreading diffusely over the pleura. One tumour was biphasic, with mucin-containing glandular areas; two were monophasic. All three stained positively for bcl-2 protein and MIC2 gene product (CD99) and focally for keratin or EMA. Two patients were disease-free at 1 year and at 9 months. The third died 5 months after diagnosis. The authors concluded that synovial sarcoma should be considered as a possible primary pleural cancer, especially in a young patient with a localized mass. They added that bcl-2 staining may perhaps help distinguish it from mesothelioma, especially monophasic forms, within a panel of antibody stains. No fresh tissue was available for chromosome testing by cytogenetics.

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 series: clinicopathological and immunohistochemical review of three cases
• Who was studied: Three men, aged 42, 28 and 42, with primary synovial sarcoma involving the pleura. Two were diagnosed directly. The third was found when the authors reviewed all pleural malignant mesotheliomas diagnosed at the Royal Brompton Hospital, London, since 1990, and reclassified one case.
• Exposure: Asbestos exposure was not the subject of the study. None of the three patients had a known history of asbestos exposure. Cases 1 and 2 had no known occupational exposure, and case 3 had no history of exposure. The study examined tumour tissue using a mucin stain and a panel of antibody stains, including keratin, EMA, BerEP4, AUA1, CEA, S100, desmin, CD34, bcl-2 and MIC2.
• Main results:
  • Case 1 (42-year-old man) had a biphasic synovial sarcoma. Its scattered epithelial elements contained D-PAS positive mucin and stained positively for keratin, EMA, AUA1 and BerEP4.
  • All three tumours showed focal positive staining for either keratin or EMA in the sarcomatous elements.
  • All three tumours stained positively for bcl-2 protein and MIC2 gene product (CD99).
  • In all three patients, the underlying mass was localized rather than spreading diffusely around the pleural cavity.
  • In case 3 (42-year-old man), a thoracoscopic biopsy initially suggested malignant mesothelioma. The tumour was later reclassified as a monophasic synovial sarcoma. This patient died 5 months after initial diagnosis.
  • After treatment, case 1 remained well and free of disease at 1 year. Case 2 (28-year-old man, monophasic tumour) remained well and disease free at 9 months.
• The authors' conclusion: The authors concluded that clinicians should be aware of synovial sarcoma as a possible primary pleural malignancy, especially in a young patient with a localized mass. They added that bcl-2 positivity may perhaps prove a helpful addition to the antibody panel when distinguishing it from mesothelioma, alongside an appropriate histological pattern.
• Limitations the authors state:
  • No fresh tissue was available in any of the three cases to look by cytogenetics for the X;18 chromosome translocation found in many synovial sarcomas.
  • Specific immunohistochemical markers for mesothelioma were not used. The authors considered that none was yet established as more specific than a negative panel of carcinoma markers.
  • In case 1, the glandular foci had been cut through in later sections, so bcl-2 and MIC2 staining could not be assessed in the epithelial component.

Topics

Medical terms in this study, explained in our Lexicon: Synovial Sarcoma, Pleura, Pleural Cavity, Malignant Mesothelioma, Mesothelioma, Sarcoma, Biphasic Mesothelioma.

Related studies

• Synovial sarcoma of the pleura: a clinical and pathologic study of three cases — A.S. Colwell, J. D'Cunha, et al. (2002)
• The diagnostic utility of reduced immunohistochemical expression of SMARCB1 in synovial sarcomas: a validation study — J. Ito, N. Asano, et al. (2016)
• NY-ESO-1 expression in synovial sarcoma and other mesenchymal tumors: significance for NY-ESO-1-based targeted therapy and differential diagnosis — J.P. Lai, P.F. Robbins, et al. (2012)
• Pleural malignant mesothelioma versus pleuropulmonary synovial sarcoma: a clinicopathological study of 22 cases with molecular analysis and survival data — S. Klebe, S. Prabhakaran, et al. (2018)
• Pericardial synovial sarcoma, a potential for misdiagnosis: clinicopathologic and molecular cytogenetic analysis of three cases with literature review — Y. Cheng, W. Sheng, et al. (2012)
• Calretinin and other mesothelioma markers in synovial sarcoma: analysis of antigenic similarities and differences with malignant mesothelioma — M. Miettinen, J. Limon, et al. (2001)

Browse more research in Histopathology, or return to medical research.