This is a T3a renal cell carcinoma due to its extension into the left renal vein.

The interesting aspect of this case is the tumor extension into the vein has caused occlusion of the left testicular vein with a resultant varicocele.  The traditional teaching on identifying a left sided varicocele has been to examine for a renal tumor.  A fellowship classic for MRCP or FRCS.

Here, you have a radiological example to prove it.