Primary renal synovial sarcoma – a diagnostic dilemma

Soft tissue sarcomas are rare mesenchymal tumors that comprise 1% of all malignancies. Synovial sarcoma accounts for 5% to 10% of adult soft tissue sarcomas and usually occurs in close association with joint capsules, tendon sheaths, and bursa in the extremities of young and middleaged adults.1 Synovial sarcomas have been reported in other unusual sites, including the head and neck, thoracic and abdominal wall, retroperitoneum, bone, pleura, and visceral organs such as the lung, prostate, or kidney.2 Primary renal synovial sarcoma is an extremely rare tumor accounting for <2% of all malignant renal tumors.3 To the best of our knowledge, fewer than 50 cases of primary renal synovial sarcoma have been described in the English literature.4 It presents as a diagnostic dilemma because of the dearth of specific clinical and imaging findings and is often confused with benign and malignant tumors. The differential diagnosis includes angiomyolipoma, renal cell carcinoma with sarcomatoid differentiation, metastatic sarcoma, hemangiopericytoma, malignant solitary fibrous tumor, Wilms tumor, and malignant peripheral nerve sheath tumor. Hence, a combination of histomorphologic, immunohistochemical, cytogenetic, and molecular studies that show a unique chromosomal translocation t(X;18) (p11;q11) is imperative in the diagnosis of primary renal synovial sarcoma.4 In the present report, we present the case of a 38-year-old man who was diagnosed with primary renal synovial sarcoma. Amulya Yellala MD,a Prashant Mukesh Jani, MD,b Ariel Sandhu, MD,b Naga Sai Krishna Patibandla, MD,a Larisa Greenberg, MD,b Suzanne Schiffman, MD,c and Dulabh Kaur Monga, MDb