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Biphasic synovial sarcoma of the mediastinum with sternal invasion

Published:September 30, 2022DOI:https://doi.org/10.1016/j.amjms.2022.09.015

      Case presentation

      A 24-year-old woman presented with cough and dyspnea without obvious inducement over 10 days. Here body weight decreased by approximately 1 kg since the onset of the disease. The chest computed tomography revealed a large soft tissue density mass lesion located in the superior mediastinum with heterogeneous enhancement (Figure 1A-C) and sternal invasion (Figure 1D, arrow). Mild pericardial and pleural effusion with pericardial thickening was noted (Figure 2A-B, arrow). There was no evidence of synovial tissue involvement outside the thorax. CT-guided percutaneous biopsy revealed the mass as a spindle cell variant of adenocarcinoma. Immunohistochemistry of the biopsied sample showed cytokeratin 7 (CK7) (+), vimentin (Vim) (+) (Figure 3A-B), and epithelial membrane antigen (EMA) (+). A biphasic type of tumor consists of distinct epithelial and spindle cell components. Both epithelial and spindle cells are reactive to CK and EMA, whereas only the spindle cells are positive for Vim. Finally, a diagnosis of biphasic synovial sarcoma with a spindle cell component and an epithelial component of the mediastinum was confirmed.
      Synovial sarcoma is a rare malignant tumor of soft tissues and mainly occurs in the deep articular soft tissues of the extremities,
      • Paquette M
      • Truong PT
      • Hart J
      • et al.
      Primary sarcoma of the mediastinum: a report of 16 cases referred to the British Columbia Cancer Agency.
      mostly the lower extremities. It can also occur in the pericardium, lung, nasopharynx and other rare sites. Synovial sarcoma occurring in the mediastinum is extremely rare, and it was first reported by Witkin et al. in 1989.
      • Witkin GB
      • Miettinen M
      • Rosai J
      A biphasic tumor of the mediastinum with features of synovial sarcoma. A report of four cases.
      It is divided into biphasic, monophasic spindle cell, monophasic epithelial cell, and poorly differentiated types. It can occur in individuals of a broad age range, with a peak incidence between 10 and 35 years of age. The clinical manifestations are mostly non-specific, and the majority of them are dyspnea, cough, and chest and back pain, similar to the symptoms observed in this case. Mediastinal synovial sarcoma with a low clinical incidence often lacks typical clinical manifestations and imaging signs. Immunobiology and cytogenetics of tumor tissue play a crucial role in the diagnosis of the disease.
      • Terra SBSP
      • Aesif SW
      • Maleszewski JJ
      • et al.
      Mediastinal synovial sarcoma: clinicopathologic analysis of 21 cases with molecular confirmation.
      Tumor cells are often positive for Vim and EMA, but negative for CD34. Although a genetic examination of the tumor was not performed in this patient, the results of tumor immunohistochemistry supported the diagnosis of the disease.
      Here, the onset of disease in the patient was early and the volume of the mediastinal neoplasm was large. Low density areas of necrosis and invasion of the adjacent structures were observed, showing obvious malignant biological characteristics.
      Herein, we reported a case of biphasic synovial sarcoma in a young woman with sternal invasion, which was consistent with available reports.

      Declaration of Competing Interest

      All authors have no conflict of interest and grant to declare.

      References

        • Paquette M
        • Truong PT
        • Hart J
        • et al.
        Primary sarcoma of the mediastinum: a report of 16 cases referred to the British Columbia Cancer Agency.
        J Thorac Oncol. 2010; 5: 898-906
        • Witkin GB
        • Miettinen M
        • Rosai J
        A biphasic tumor of the mediastinum with features of synovial sarcoma. A report of four cases.
        Am J Surg Pathol. 1989; 13: 490-499
        • Terra SBSP
        • Aesif SW
        • Maleszewski JJ
        • et al.
        Mediastinal synovial sarcoma: clinicopathologic analysis of 21 cases with molecular confirmation.
        Am J Surg Pathol. 2018; 42: 761-766