Benign retroperitoneal fibrosis and renal cell carcinoma.

We report benign retroperitoneal fibrosis associated with renal cell carcinoma in a 56-year-old woman. Based on the preoperative evaluation and initial surgical exploration, the retroperitoneal mass was assumed to be metastatic renal cell carcinoma and chemotherapy rather than surgical resection was offered to the patient. A second opinion was sought and repeat exploration revealed a resectable cell carcinoma and retroperitoneal tissue that was pathologically benign idiopathic retroperitoneal fibrosis. This report emphasizes that a patient with an otherwise resectable primary tumor must undergo multiple, deep biopsies of retroperitoneal masses before making a presumptive diagnosis of malignant retroperitoneal fibrosis secondary to metastatic cancer.