Benign retroperitoneal neurilemoma without von Recklinghausen's disease: a rare occurrence.

We describe a rare case of a primary retroperitoneal neurilemoma that was confused initially on ultrasonography and computerized tomography for a renal carcinoma. These tumors vary in vascularity on arteriography, are more often solid than cystic and usually are benign in the absence of von Recklinghausen's disease. The preferred treatment is wide surgical excision.