Pleomorphic xanthoastrocytoma （Kepes）の1例

A CASE OF PLEOMORPHIC XANTHOASTROCYTOMA

　抄録　Pleomorphic xanthoastrocytomaは1979年Kepesが提唱して以来未だ症例の少ない腫瘍であり，その1例を経験したので報告する。症例は11歳，男児で，けいれんにて発症した。CT scanにて右前頭葉に嚢腫が存在し，造影後嚢腫壁の一部が増強された。血管写では右前頭葉に無血管野が存在した。手術所見は大きなcystが存在し，cyst wallの一部に赤褐色の腫瘍を認め，これを摘出した。組織学的に腫瘍は多形性の強い細胞からなり，巨細胞，多核細胞の出現率が高いが，分裂像，壊死像の所見は認めなかった。腫瘍細上泡はGFAP陽性の縮胞が多く，レチクリン染色にて軽度線維の増加を認めた。電顕所見ではglial filamentとfat dropletを認めた。以上の所見よりpleomorphic xanthoastrocytomaと診断した。この腫瘍概念は病理組織学的所見と臨床上の悪性度が一致しない点において重要である。臨床的には若年者に多くてんかん発作で発症し，前頭側頭葉に嚢腫を有する腫瘍で，生命予後は良好である。今後症例が増加することにより，このastrocyte山来と考えられる腫瘍の病態が明確になってくると考えられる。

A case of pleomorphic xanthoastrocytoma (Kepes) is reported. This patient was a 12-year-old boy with a history of convulsive seizure. Neurological examination on admission showed no abnormality. Plain CT scan revealed a well defined low density area with calcification in the right frontal lobe. A part of peripheral portion of low density area were well enhanced with contrast media. At operation, there was a cyst containing xanthochromic fluid in the right frontal lobe. A part of cyst well near the cerebral surface was reddish hard. Total removal of nodular tumor and subtotal removal of the cyst wall were per-formed. He has been doing well for these 3 years following craniotomy and has no deficit without CT evidence of recurrent tumor.

Histologically the tumor cells displayed marked pleomorohism. However either necrosis or mitosis were not seen. Frequently these cells had vacu-olated or foamy cytoplasm. There were many of the giant cells and multinucleated cells. In some area, these tumor cells were surounded by a fine network of reticulin fibers. Electron mic-roscopically the tumor cells were occasionally filled with glial filament and lipid granules were seen. Immunoperoxidase technique revealed GFAP in the cytoplasm of the tumor cells.

This case was considered to be pleomorphic xanthoastrocytoma first proposed by Kepes.