Primary primitive neuroectodermal tumor (PNET) of the kidney with venous thrombus.

Primitive neuroectodermal tumors of the kidney are rare, the diagnosis usually being made at histopathology. A young adult presented with a painful left renal mass. CT Scan of the abdomen revealed a large necrotic tumor of the left kidney. At surgery the patient was found to have a venous thrombus confined to the renal vein. Radical nephrectomy was done. Histopathology showed a round cell neoplasm with typical Homer Wright rosette formation and positive staining for neuron specific enolase (NSE) and MIC-2 on immunohistochemistry. The patient is undergoing multidrug chemotherapy and is alive and well at a follow up of nine months.