[A Case of Desmoid Tumor Initially Diagnosed as a Metastasis from Renal Cell Carcinoma --A CASE REPORT-].

We report a case of desmoid tumor that was initially diagnosed as metastasis from renal cell carcinoma. A follow-up computed tomographic (CT) scan after nephrectomy for renal cell carcinoma in a 64-year-old man revealed a right retroperitoneal tumor 3.5 cm in diameter. Though the CT density of the tumor was similar to that of muscles, we first suspected metastasis from renal cell carcinoma or other cancer because the tumor growth was relatively fast. We resected the tumor. The pathological diagnosis was desmoid type fibromatosis. We also review six cases of desmoid tumors after nephrectomy for renal cell carcinoma reported in Japan. Careful followup is required for the patients with desmoid tumors because of frequent recurrence.