視交叉から両側の後方視神経路にかけて発生したCystを伴う視神経膠腫の1例

A Case of Cystic Optic Glioma involving Chiasma and Bilateral Posterior Optic Pathway

I．はじめに

　視神経膠腫は2-5歳の幼少時に好発する腫瘍で，原発性脳腫瘍のO．6-1.2％，小児頭蓋内腫瘍の約5％を占める．腫瘍は視神経路のいずれの部位からも発生しうるがその好発部位は眼窩内視神経と視交叉である．視交叉より後方の視神経路での発生は比較的少なく特に両側性となるとまれである．一方組織学的にはpilocytic astrocytomaが主体でmicrocystをみることはあるが，小脳に発生するものと異なり大きなcystを伴うことはまれである．今回われわれは視交叉から後方の両側の視神経路にかけて発生したcystを伴う視神経膠腫を経験し，確定診断に苦慮したので報告する．

A case of cystic optic glioma involving chiasma and bilateral posterior optic pathway was reported. A 26-year-old male was admitted to our hospital complaining of dysarthria and left hemiparesis. CT, MRI revealed a cystic tumor at the right basal ganglia to midbrain, a calcified one at the bilateral optic tract and left tempor-al to thalamic region, and a small one at the chiasma.

Radiotherapy and chemotherapy were performed be-cause anaplastic astrocytoma was suspected after stereotactic biopsy of the tumor at the right basal gan-glia. The subsequent MRI showed continuity among the above three lesions to be well defined. About 2 years later, however, enlargement of the cyst, tumor in-vasion beyond the optic pathway and growth of the chiasmal lesion were noted, and direct surgery to the chiasmal lesion was performed. The chiasma was swol-len and grayish soft tumor tissue was partly resected after aspiration of the intrachiasmal cyst. The definitive pathological diagnosis was pilocytic astrocytoma.

This case was designated as a peculiar optic glioma in the following respects ; the patient was an adult man suf-fering from dysarthria and left hemiparesis, the tumor involved not only the chiasma and the bilateral optic tract, but also the outside optic pathway and was accompanied by a large cyst.