Hemangiopericytoma of renal sinus expanding to the renal hilum: an unusual presentation causes misinterpretation as transitional cell carcinoma.

We report a case of renal hemangiopericytoma occurring in renal sinus and expanding to the renal hilum. This unusual presentation caused misinterpretation of this tumor as transitional cell carcinoma of the renal pelvis clinically. The patient who was a 30-year-old woman had a relatively well demarcated solid tumor, 8 x 6 cm, in the renal sinus of the left kidney.