Primary Ewing's Sarcoma/Primitive Neuroectodermal Tumor of of Kidney - a Diagnostic Dilemma

Among the group of small round cell tumors of kidney Ewing’s sarcoma/PNET is a very rare entity which has aggressive clinical course. We report a case of renal mass in 24 years old male which was histologically diagnosed as small round cell tumor of kidney. Arrangement of the malignant cell along with vascular network in a filigree pattern was suspicious for a diagnosis of Ewing’s sarcoma/PNET which was confirmed by positivity of CD 99 immunohistochemically. Thus careful histological observation and immunohistochemical stains can give the proper diagnosis of primary Ewing’s sarcoma/PNET thus removing the diagnostic dilemma in the group of small round cell tumors.