Evaluating the clinico-pathological features including the immunohistochemical and molecular landscape of synovial sarcoma cases from a tertiary care cancer referral centre in India.

BACKGROUND: Synovial sarcoma (SS) is a malignant mesenchymal neoplasm with variable epithelial differentiation, with a propensity to occur in young adults. The pathognomonic t(X;18) chromosomal translocation and subsequent development of the SS18:SSX fusion oncogenes are the driver of the distinct genomic features. AIM: To study the Clinicopathological, immunohistochemical and molecular features of SS occurring in all the organ systems. METHOD: A retrospective observational study was conducted over a period of 4 years at a tertiary cancer centre. RESULT: One hundred eight patients were included in the study based on exclusion and inclusion criteria. The median age of patients was 30.5 years and mean tumor diameter was 10.5 cm. Most common site was lower limb followed by lung, and arm. 50 patients underwent surgery and 49 patients received adjuvant chemotherapy or radiotherapy. 87 patients (81%) presented with monophasic subtype and 21 (19%) with biphasic subtype. The most helpful immunohistochemical markers for diagnosis and exclusion of close differentials were TLE1, EMA, Pancytokeratin, S-100, BCL2, and CD99. Molecular diagnostic confirmation was attained in 10 out of 15 patients. On median follow-up of 7.58 months, mean 4-year overall survival of the patients was 91.39%. CONCLUSION: Meticulous pathologic evaluation and awareness of the typical and atypical histology of SS along with the apt application of immunohistochemical marker such as TLE1 and/or cytogenetics (SYT translocation) assist in precise recognition of this not so common entity. The main therapeutic modality is surgical excision with negative margins, with the addition of radiotherapy and/or chemotherapy based on patient and tumour characteristics.