[Renal cell carcinoma in a horseshoe kidney: report of two cases]

We report 2 patients with renal cell carcinoma in a horseshoe kidney. A renal tumor was diagnosed during evaluation of right humeral metastatic cancer of unknown origin in case 1 (64-year-old male) and gross hematuria in case 2 (54-year-old male). Both patients underwent radical nephrectomy with division of isthmus and retroperitoneal lymph node dissection. The tumors were staged pathologically as pT2bpN0pV0pM1(oss) and pT3pN0pV1bM0, respectively. Only 27 cases of renal cell carcinoma developed in a horseshoe kidney, including the present two cases, have been reported in the Japanese literature. The blood supply to the horseshoe kidney and its evaluation by preoperative angiography were discussed.