SYNOVIAL SARCOMA- A POTENTIAL DIAGNOSTIC PITFALL ON FNAC

• Poornima Patel,*  
• Neethu G V,  
• Anusha Somanath

Abstract

Synovial sarcoma is a malignant mesenchymal neoplasm of uncertain origin. It arises most frequently in the extremities, mostly the lower extremities. The diagnosis of synovial sarcoma can be challenging owing to its morphological heterogeneity. Histologically, it can be of three subtypes: Monophasic, Biphasic and Poorly differentiated. Transducin-Like Enhancer 1(TLE1) is a transcriptional corepressor and is a sensitive and specific marker for synovial sarcoma which is helpful in distinguishing synovial sarcoma from histologic mimics. This case report presents a 48year old female with swelling over right forearm since 1 year which was misdiagnosed on FNAC as Benign spindle cell lesion, probably Schwannoma. Surgery was done and on histopathological examination, it was diagnosed as Biphasic synovial sarcoma. It was confirmed by TLE1 immunohistochemistry which showed diffuse strong nuclear positivity. Cytology sometimes fails to sample the epithelial component in biphasic synovial sarcoma, preventing a specific diagnosis. The exact subtyping of spindle cell tumours is difficult on cytology owing to their complex heterogeneity. Synovial sarcoma is an aggressive neoplasm, however it responds well to treatment including surgery and chemotherapy. Therefore, early and correct diagnosis of synovial sarcoma is vital.

Keywords

Synovial sarcoma, malignant mesenchymal neoplasm, biphasic neoplasm, TLE1