[A Case of Adult Mature Teratoma Located in Retroperitoneum].

A 35-year-old man wasreferred to our hospital for treatment of a right adrenal tumor detected by ultrasonography during a physical check-up. Contrast-enhanced abdominal computed tomography revealed a poorly enhanced 74 mm tumor situated adjacent to the upper pole of the right kidney. The tumor consisted of fat with peripheral calcification. Magnetic resonance imaging also revealed a right retroperitoneal tumor with fatty contents and well-circumscribed capsule. The endocrine examination revealed the tumor as non-functioning. These findings were suggestive of a right adrenal myelolipoma. We performed laparoscopic right adrenalectomy because of its large size and malignant potency. The pathological examination revealed the retroperitoneal tumor asa mature teratoma existing apart from the adrenal gland. Primary retroperitoneal teratomasare relatively rare. Herein, we report thiscas e of adult mature teratoma occurring in the retroperitoneum.