Anaplastic sarcoma of the kidney: Case report and literature review.

We present a case of a 22-year-old female with gross hematuria for 1 month. A 9.5-cm tumor was found at her left kidney. On suspicion of a renal cancer, she received left nephrectomy. Histologically, it was a hypercellular tumor with undifferentiated anaplastic neoplastic cells in fascicular sheets intermixed with chondroid nodules. The differential diagnoses included anaplastic sarcoma of the kidney (ASK), anaplastic Wilms tumor, mesenchymal chondrosarcoma, sarcomatoid renal cell carcinoma, clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, congenital mesoblastic nephroma, and synovial sarcoma. Based on the results of the work-up and literature review, ASK was diagnosed. The postoperative recovery was uneventful, and the patient began adjuvant chemotherapy (Ifosfamide [1800 mg/m²] and Epirubicin [60 mg/m²]) 5 weeks after the operation. Herein, we present this case to share the experience on an extremely rare entity.