Intravenous extended liposarcoma arising from renal sinus

: Liposarcoma arising from the renal sinus is rare and there have been no reports of intravenous extended liposarcoma of the renal sinus thus far. We report a case of liposarcoma of the renal sinus that extended into the renal venous lumen. A 58‐year‐old woman was referred to our hospital for an intravascular fatty tumor of the right renal vein incidentally discovered by an abdominal screening ultrasonogram. Computer tomography revealed a fatty tumor extending from the right kidney to the right renal vein with no evidence of metastatic lesions. Total right nephrectomy and extirpation of the intravascular tumor of the right renal vein were carried out. Pathological findings showed well‐differentiated liposarcoma of the renal sinus. The tumor invaded to the right renal vein and the renal parenchyma.