Synovial sarcomas account for 7% to 10% of all human soft-tissue sarcomas. The tumors arise at any age, but affect mainly young adults and more commonly males. Clinically, they appear as deep-seated slowly growing masses. In more than half of the cases, metastases develop, primarily to the lungs but also to the lymph nodes and bone marrow. A specific translocation, t(X; 18)(p11.2; q11.2), is found in more than 90% of reported synovial sarcoma, including biphasic, monophasic, and poorly differentiated tumors. The breakpoints of the t(X; 18) have been cloned and shown to involve the fusion of the SYT gene at 18q11 to either of two highly homologous genes at Xp11 called SSX1 and SSX2. The SYT-SSX1 fusion is associated with biphasic morphology and a worse prognosis, whereas the SYT-SSX2 fusion tends to show monophasic morphology and better outcome.
Human diseases in ICD-11 classification [BR:br08403]
Malignant neoplasms, except primary neoplasms of lymphoid, haematopoietic, central nervous system or related tissues
Malignant neoplasms, stated or presumed to be primary, of specified sites, except of lymphoid, haematopoietic, central nervous system or related tissues
Malignant mesenchymal neoplasms
2B5A Synovial sarcoma, primary site
H00050 Synovial sarcoma