PNET of kidney: Report of four cases

Primitive neuroectodermal tumor (PNET) of kidney is a rare tumor of kidney with only a few published reports. We report here four cases of PNET of kidney in the age group between 30 and 50 years who had complaints of vague pain and lump in loin. Hematuria was present in one case. Imaging of all cases revealed renal mass. The pathologic findings were consistent with PNET in all cases–confirmed by immunohistochemistry with diffuse membrane positivity of tumor cells of CD99. We could not do fluorescent in situ hybridization to demonstrate EWS-FLI-1 gene fusion. Each case was in the advanced stage. However, after giving postoperative radiotherapy and chemotherapy patients are still alive. Reporting of these cases are important as we got them in a short span of 3 years. In view of its poor prognosis, aggressive nature and different therapeutic approach– renal PNET should be differentiated from other small blue round cell tumors like neuroblastoma, rhabdoid tumor of kidney, nephroblastoma, small cell carcinoma, synovial sarcoma (monophasic, poorly differentiated) and non-Hodgkin lymphoma (NHL) by immunohistochemistry, cytogenetic, and molecular genetics study to see the different gene rearrangements in NHL and 3p deletion in small cell carcinoma.