RESUMO
Primary synovial sarcoma [SS] of kidney is very rare and difficult to diagnose. Here, we present a case of a 21-year-old female clinically diagnosed as renal cell carcinoma. Right nephrectomy specimen showed a cystic tumor in the upper pole of kidney with areas of hemorrhage and solid growth. Histologically, it showed poorly differentiated cells with hemangiopericytoma-like vascular pattern. Morphologic and immunohistochemical features were compatible with the diagnosis of poorly differentiated SS of kidney. Primary renal SS is a recently described entity. To the best of our knowledge, approximately 34 cases have been reported till date and this is the eighth documented case of poorly differentiated variant. Most of the time, poorly differentiated SS of kidney exhibits hemangiopericytoma like histology. Reverse transcriptase-polymerase chain reaction analysis to demonstrate SYT-SSX fusion gene transcript helps to confirm the diagnosis