6年間の囊胞形成過程を観察し得たgangliocytomaの1例

A Case of Gangliocytoma: A Six-year Follow-up of Cyst Formation

Ⅰ．はじめに

　Gangliocytomaは中枢神経系に生じる稀な腫瘍であり，WHO（World Health Organization）ではneuronal and mixed neuronal-glial tumorsに分類される¹⁾．脳腫瘍全国統計によればgangliogliomaを含めてもわずか0.4％の頻度であり症例報告も少ない^5,6,9)．今回われわれは，6年間にわたり画像の変化を観察し得た頭頂葉のgangliocytomaの1例を経験したので報告する．

　We report a case of gangliocytoma at a cortical and subcortical area in the right parietal lobe. The patient had a generalized seizure at 11 years of age. The MRI shows an ill-demarcated high intensity area in T2 weighted images including an enhancing tumor of 10mm in diameter. At first,the tumor was carefully followed up because of its small size and the surgical risk. Three years after the onset,a cyst formed at the area of the brain edema adjacent to the tumor. The cyst gradually grew to 21mm in diameter,the edema had disappeared,and the size of the tumor became smaller (7mm) within the next 3 years. A mural nodule,jelly-like tumor with calcification was totally removed and diagnosed as gangliocytoma. The cyst fluid was watery-clear,its wall did not contain any tumor. This is the first report of a six-year follow-up of cyst formation of gangliocytoma supporting the concept that edema is a precursor to central nervous system peritumoral cyst formation based on the similar observation of hemangioblastomas.