Abstract
Synovial sarcomas are relatively common intermediate-to-high-grade malignant soft tissue tumors, often with an initial indolent course. And among the sarcomas primary intra-abdominal synovial sarcoma is a relatively rare entity that may present with an abdominal mass and diagnosis is usually confirmed by immunohistochemistry. The authors report a case of a 46-year-old man who presented with a large palpable abdominal mass. Contrast-enhanced computed tomography (CT) scan showed a large well-defined heterogeneous intra-abdominal mass filling the entire pelvis and extending upwards till the subhepatic region causing displacement of intra-abdominal organs. However, no other focal lesions were seen in the solid organs. The same findings were confirmed on surgery. Histopathology was suggestive of desmoid tumor/hemangiopericytoma. Immunohistochemistry showed positive markers corresponding to synovial sarcoma. The patient was advised to undergo chemotherapy which was refused and follow-up was lost. After 10 months, patient presented for follow-up CT, which showed marked increase in size of the lesion.