副腎骨髄脂肪腫と鑑別困難であった後腹膜奇形腫の1例

Abstract

59歳男.上腹部痛が出現し, 近医にて胆石症を指摘され消化器内科へ紹介来院したが, 腹部CTで左後腹膜腔の腎上極部に脂肪成分に富む石灰化を伴った腫瘤を認め, 副腎骨髄脂肪腫の疑いで泌尿器科へ転科となった.臨床検査所見および画像所見から臨床診断として副腎骨髄脂肪腫を疑い, 腫瘍摘出術を施行した.摘出腫瘍の病理組織学的所見では, 腫瘍は結合組織と脂肪成分を主とし, 一部に骨髄組織も認められ, 他に粘液腺, 筋組織, 骨化した気管支軟骨, 気管支上皮と思われる繊毛上皮, 神経組織, 砂粒体なども見られた.画像上の石灰化は骨化した気管支軟骨であった.悪性を思わせる所見はなく, 本症例は三胚葉由来の成熟奇形腫と診断された

A 59-year-old man presented to our hospital suspected of having cholelithiasis. Computed tomography (CT) scan revealed a left retroperitoneal solid tumor cephalad to the kidney, 7 x 8 x 9 cm in size with mostly a fatty density area and focal calcification. Magnetic resonance imaging (MRI) on T1 and T2 weighted images showed a high intensity mass. Angiography revealed the hypovascular tumor. Although we had suspected it to be an adrenal myelolipoma, tumorectomy was performed because of its size. Pathological diagnosis was mature teratoma. Although retroperitoneal teratoma contains fas, cyst, soft tissue and calcification, the proportion of fat in the tumor is usually less than that of adrenal myelolipoma. In our case, the tumor contained more fat than the 'typical' retroperitoneal teratoma, which led to the misdiagnosis.