Primary extraosseous ewing sarcoma of the kidney with level III inferior vena cava thrombus.

Ewing sarcoma typically presents as a skeletal-based tumor, with rare instances of peripheral primitive neuroectodermal tumor (PNET) arising in the soft tissues. Few examples of organ-based PNETs have been previously described in the literature. These tumors are exceedingly rare as a primary renal neoplasm. To our knowledge, this is the first report documenting a primary extraskeletal Ewing sarcoma of the kidney with thrombus extending into the intrahepatic inferior vena cava thrombus (level III).