[A case of cystic optic glioma involving chiasma and bilateral posterior optic pathway].

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 temporal to thalamic region, and a small one at the chiasma. Radiotherapy and chemotherapy were performed because anaplastic astrocytoma was suspected after stereotactic biopsy of the tumor at the right basal ganglia. The subsequent MRI showed continuity among the above three lesions to be well defined. About 2 years later, however, enlargement of the cyst, tumor invasion beyond the optic pathway and growth of the chiasmal lesion were noted, and direct surgery to the chiasmal lesion was performed. The chiasma was swollen 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 suffering 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.