Anaplastic sarcoma of the kidney (ASK) is a relatively newly recognized pediatric renal tumor. The present patient, a 13-year-old boy with a large renal mass, underwent surgery. Pathological findings showed proliferation of short spindle-shaped cells with anaplastic features including multiple foci in hyaline cartilage. Complex chromosomal abnormalities were detected in the tumor cells. Postoperative chemotherapy with the regimen for Ewing's sarcoma achieved complete remission but the tumor recurred and the patient died during re-induction chemotherapy. Autopsy indicated the cause of death as duodenal hemorrhage. Because there were no viable tumor cells, the recurrent tumor was considered to have been completely cured by chemotherapy. ASK is a very rare tumor, of unknown pathogenesis, and no standard treatment has yet been established, but the tumor cells may be responsive to chemotherapy. Further study is needed to establish the optimal treatment strategy.
Keywords: Wilms tumor; anaplastic sarcoma of the kidney; autopsy; children; rare renal tumor.
© 2013 The Authors. Pediatrics International © 2013 Japan Pediatric Society.