23 year old female presented with pain and heaviness in left side for last 3 months associated with burning micturition without hematuria. Pain was gradually progressive in nature. On examination -P/A: Soft, non tender, non distended, a solid mass measuring approx.. 10 cms mass was palpable in the left hypochondrium extending into lumbar region. CT scan showed left renal mass which was completely replacing renal parenchyma with perinephric extension and left renal vein and infra diaphragmatic IVC tumoral thrombus with tiny focal lesion in the liver. what could b the diagnosis??