後腹膜に発生した未分化神経外胚葉性腫瘍

A case of retroperitoneal peripheral neuroectodermal tumor（PNET）originated from retroperitoneal space

　症例は47歳，女性。2003年12月，貧血の精査中に右腎と下大静脈の間に12cm大の充実性腫瘍を認めた。後腹膜腫瘍の診断にて摘出術を施行した。病理所見は未分化神経外胚葉性腫瘍（primitive neuroectodermal tumor：PNET）と診断された。後腹膜PNETは世界で18例目の報告であった。きわめて予後不良とされるが，手術療法のみで術後2年4か月経過した現在，再発なく経過している。

　Peripheral neuroectodermal tumor is a rare malignant soft tissue tumor derived from a neural crest. This tumor is believed to be the same as Ewing sarcoma immunohistochemically except for their differentiation. Its prognosis is extremely poor. We report a case of PNET arising from the retroperitoneal cavity. A 47-year-old woman presented with anemia and computed tomography（CT）imaging revealed right retroperitoneal solid mass with adherence to right kidney and right adrenal gland. The tumor was successfully resected together with right kidney and a part of IVC（inferior vena cava）wall. The pathological diagnosis was PNET. Although she did not consent to an adjuvant therapy, she has been doing well without recurrence for 52 months after the operation.（Rinsho Hinyokika 61：69-71, 2007）