Primary Ewing's sarcoma/primitive neuroectodermal tumor of the kidney and its clinical features.

Ewing sarcoma family tumor is a malignant tumor that is primarily of bone origin; it rarely occurs in the kidney. A 22-year-old woman presented with hematuria. Computed tomography revealed a 6 × 6-cm mass in the lower pole of the right kidney with invasion into the right renal vein. A right laparoscopic radical nephrectomy was performed. The tumor was completely encapsulated. Based on the small-round-cell histology, diffusely CD99-positive tumor cells, and EWS (ex7)-FLi1 (ex6) fusion gene break point transcript, we diagnosed Ewing sarcoma/primitive neuroectodermal tumor of the kidney. After surgery, eight cycles of adjuvant chemotherapy including vincristine, doxorubicin (Adriamycin®), cyclophosphamide, ifosfamide, and etoposide were given. No evidence of recurrence has been observed 13 months from diagnosis. This was a rare Ewing sarcoma family tumor in the kidney of a young female with no remarkable family medical history.