後腹膜Inflammatory myofibroblastic tumorの1例

Abstract

46歳女.尿潜血を主訴とした.尿潜血のスクリーニングのため施行された腹部超音波断層検査で右腎外側に長径5cmと4cmの充実性腫瘍を認めた.腹部CTでは右腎外側に腎実質を圧排するように2つのiso-densityな腫瘍が存在し, 造影後期相では腫瘍辺縁部が比較的濃染された.腹部MRIで腫瘍はT1強調像で低信号, T2強調像で高信号を基調としており, 腫瘍辺縁部の信号強度がやや低く, 造影すると辺縁部がよく濃染された.画像所見上, 悪性線維性組織球腫あるいは脂肪成分に乏しい脂肪肉腫が疑われ, 後腹膜悪性腫瘍の術前診断のもとに, 腰部斜切開, 後腹膜アプローチにて腫瘍摘出および右腎摘除術を行った.腎との癒着や脂肪肉腫の術中迅速病理診断に基づいて腎の合併切除を行った.免疫組織化学染色から後腹膜原発のinflammatory myofibroblastic tumorと診断された.経過観察中で再発は認めていない

Here we report a rare case of inflammatory myofibroblastic tumor of the retroperitoneal space. A 46-year-old woman had had microscopic hematuria for 5 years. Ultrasonographic examination for screening revealed two solid tumors adjacent to the right kidney. These tumors were suspected to be malignant fibrous histiocytoma or liposarcoma by computed tomography and magnetic resonance imaging. She underwent resection of these retroperitoneal tumors and additional right nephrectomy because these tumors were adhered to the kidney and liposarcoma was highly suspected on frozen sections. Histopathologic examination finally revealed that the tumors were inflammatory myofibroblastic tumor arising within Gerota's fasia. She has been followed up for 9 months without any evidence of local recurrence.