[Primary synovial sarcoma of the kidney]

Area of Science:

• Oncology
• Pathology
• Molecular Biology

Background:

• Synovial sarcoma is a rare soft tissue malignancy, with primary kidney involvement being exceptionally uncommon.
• Understanding the molecular drivers and diagnostic markers is crucial for accurate diagnosis and treatment of rare tumors.

Observation:

• Two patients presented with primary renal tumors exhibiting aggressive features, including vascular invasion into the inferior vena cava and right atrium (Case 1) and extensive metastatic disease to retroperitoneal lymph nodes and lungs (Case 2).
• Histopathological examination revealed monophasic and poorly differentiated tumors, with immunohistochemical staining positive for vimentin and focally for epithelial membrane antigen, but negative for keratins, S-100 protein, CD34, smooth muscle actin, and desmin.

Findings:

• Reverse transcription-polymerase chain reaction (RT-PCR) analysis of tumor tissue successfully identified the characteristic SYT-SSX1 fusion gene transcript in both cases.
• The presence of the SYT-SSX1 fusion gene is a definitive molecular hallmark for the diagnosis of synovial sarcoma.

Implications:

• The confirmation of primary kidney synovial sarcoma highlights the importance of considering rare diagnoses in renal masses with aggressive clinical presentation.
• Accurate molecular diagnosis, particularly the detection of the SYT-SSX1 fusion gene, is essential for appropriate patient management and prognosis.
• Further research into the pathogenesis and optimal treatment strategies for primary renal synovial sarcoma is warranted.