[A case of retroperitoneal teratoma in an adult resembling adrenal tumors].

A retroperitoneal teratoma arising from the vicinity of the upper pole of the right kidney in a 61-year-old woman is described. Computed tomographic (CT) scan showed well marginated fat density mass with calcification. Magnetic resonance imaging (MRI) on T1 weighted image and T2 weighted image showed a high-intensity mass above the upper pole of the right kidney. Needle biopsy under computed tomography was performed, but no specimen was obtained. The preoperative diagnosis was retroperitoneal teratoma or right adrenal myelolipoma. The tumor was resected and the histological diagnosis was benign retroperitoneal cystic teratoma.