Synchronous independent primary osteosarcoma and adenocarcinoma of kidney.

Primary osteogenic sarcomas are extremely rare tumors of the kidney. The association with a juxtaposed renal "clear" cell carcinoma would appear to be unique, although several cases of osteogenic sarcomatous differentiation have been described within so-called sarcomatoid renal cell carcinoma variants. We report a case of synchronous independent development of both renal cell carcinoma and osteogenic sarcoma within the same kidney.