Synovial sarcoma (SS): new perspectives supported by modern technology

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Synovial sarcoma (SS) is a rare and poorly understood soft tissue sarcoma.
• Histological classification includes biphasic and monophasic subtypes, with several variants described.
• Tumors often exhibit microcalcifications and squamous metaplasia.

Purpose of the Study:

• To analyze the structural, biological, and molecular pathology of synovial sarcoma.
• To correlate molecular findings with clinical outcomes.
• To highlight diagnostic markers for SS.

Main Methods:

• Review of 256 synovial sarcoma cases.
• Histopathological and ultrastructural analysis.
• Immunohistochemistry for epithelial markers (EMA, cytokeratin) and vimentin.
• Molecular analysis of chromosomal translocation t(X;18)(p11.2;q11.2) and SYT-SSX gene fusions.
• Nude-mice xenografts and in vitro cell line studies.

Main Results:

• SS displays multiphenotypic histology with epithelial and spindle cell components.
• Immunohistochemistry is crucial for diagnosis, with EMA and cytokeratin positivity in epithelial cells and vimentin in spindle cells.
• The specific chromosomal translocation t(X;18)(p11.2;q11.2) leading to SYT-SSX gene fusions is a hallmark of SS.
• SYT-SSX1 fusion is associated with poor prognosis, while SYT-SSX2 fusion indicates a better survival rate.

Conclusions:

• Synovial sarcoma exhibits significant histological and molecular heterogeneity.
• Molecular diagnostics, specifically identifying SYT-SSX fusion variants, are vital for accurate diagnosis and prognostic assessment.
• Understanding the molecular subtypes of SS can guide clinical management and improve patient outcomes.