[A case of multiple renal leiomyoma located at renal sinus and hilus]

A case of multiple renal leiomyoma of the right kidney in a 60-year-old woman, complaining of lower abdominal pain of two months duration, is presented. Ultrasonography, intravenous pyelography and CT scan showed the masses at the right renal sinus and hilus. Selective right renal angiography demonstrated very hypovascular tumors. Right radical nephrectomy was performed. There were two lobulated tumors with no connections, which were elastic hard in consistency and smooth in surface; one was 4 x 2 x 2 cm in size and located at the renal sinus between the upper and middle calyces, the other was 6.5 x 5 x 4 cm in size and located at the renal hilus, apart from the renal parenchyma, pelvis, artery and vein. Histological examination revealed these tumors to be benign leiomyoma. Both were covered with the Gerota's fascia, but not the renal capsule. The renal parenchyma was completely covered with the renal capsule histologically, although these tumors were closely attached to the parenchyma on gross examination. The tumor at renal sinus was considered to arise from the outer layer of the renal pelvis or from the blood vessel in the connective tissues at renal sinus. The tumor at renal hilus was considered to arise from the blood vessel in the connective tissues at renal hilus. This appears to be the first reported case as multiple renal leiomyoma in both Japanese and English literatures.