Pediatric clear cell sarcoma of the kidney with cavoatrial thrombus

Clear cell sarcoma of the kidney (CCSK) is a rare renal tumor. Only 4 cases of CCSK with vascular thrombus have been reported, and 2 of these were pediatric cases. One of the children had an intraatrial thrombus as well. We describe a 3-year-old boy who was diagnosed as having a Wilms tumor but did not respond to preresection chemotherapy. He underwent complete resection of the tumor under cardiopulmonary bypass. Histologic examination indicated that the tumor was a CCSK. The patient was then managed with appropriate chemotherapy and radiation therapy and is well 16 months after diagnosis.