診断に苦慮した後腹膜腔原発脂肪肉腫の1例

Abstract

60代男.約5年前, 全身倦怠感と食思不振の精査で左後腹膜腫瘍が指摘され, 左腎合併経腹的後腹膜腫瘍切除術が施行された.病理学的に悪性線維性組織球症(MFH)と診断された.術後4年目に左下肺に腫瘤を認め, 肺部分切除術を施行した.病理学的にMFHの肺転移と診断された.術後外来経過観察中に腹部CTで左後腹膜腔に腫瘤を認め, 精査加療目的で入院となった.画像検査よりMFHの局所再発と診断し, 経胸腹式到達法にて再発腫瘍に対して切除術を施行した.病理組織所見により高分化型硬化性脂肪肉腫と診断した.術後, 膵液漏を認めたが, 保存的治療にて1ヵ月後に治癒した.組織学的には切除断端陽性であったが, 脂肪肉腫には高い奏功率を示す化学療法・放射線療法がないため, 術後補助療法は施行しなかった.現在術後9ヵ月が経過し, 明らかな再発は認めていない

We report a case of retroperitoneal tumor which turned out to be liposarcoma by the histological evaluation of its recurrent tumor, although the initial tumor was diagnosed as malignant fibrous histiocytoma (MFH). A retroperitoneal tumor in a 62-year-old man was removed and pathologically diagnosed as MFH. Five years after the initial surgery, computed tomography (CT) demonstrated a recurrent tumor near the spleen. The tumor was resected together with the spleen, tail of pancreas, and connective tissue due to adhesion and diagnosed as well-differentiated liposarcoma with sclerosing component. Generally dedifferentiated liposarcoma is difficult to distinguish from MFH and the presence of a well-differentiated liposarcoma component in the adjacent adipose tissue leads to the diagnosis of dedifferentiated liposarcoma. The clinical course of the present case indicated that the initial tumor was dedifferentiated liposarcoma and the recurrent tumor developed from the surrounding well-differentiated liposarcoma.