視力低下，視野障害を呈した65歳女性

A 65-year-old Woman with Progressive Loss of Vision and Visual Field Defects

症例呈示

　症　例　65歳，女性

　主　訴　視野障害

　既往歴　61歳　硝子体出血，62歳　虫垂炎

　現病歴　1999年11月22日，突然右眼がほとんど見えなくなり，左眼も耳側が見えなくなった。さらに後頭部の鈍痛，吐き気が出現。11月26日順天堂脳神経内科を受診し12月1日入院した。入院時，両耳側半盲があり，両側上方視が3/5，下方視が4/5，左右視は5/5であった。瞳孔は正で3mm，対光反射（＋）。高次機能は問題なく，腱反射の亢進，Babinski，Hoffmann徴候などの異常反射，麻痺，失調，錐体外路徴候はなかった。この時のMRIで，視交叉付近に強くエンハンスをうける小さなmass lesionを認めた（Fig. 1）。ステロイドパルス療法1g/日，3日間を施行したところ，半盲は改善した。その後内服へ変更し外来通院となった。2000年8月28日にはプレドニゾロン5mgまで減量した。9月2日より歩行時のふらつきが出現した。歩いていると左側に傾き数回転倒するようになったため，9月12日入院した。

We report a 65-year-old Japanese lady who suffered from progressive loss of vision and visual field defect. She was well until her 61 years of the age in November of 1999, when she was found to have bitemporal hemianopsia. A small enhancing mass lesion was found in the chiasmatic region. She was treated with steroid and she noted marked improvement in her visual field defects. In August of 2000, she noted disturbance of gait. Cranial MRI revealed a mass in the right midbrain extending into the hypothalamic and thalamic regions. She was again treated with steroid with marked improvement. However, in November of 2001, she started to show somnolence and diabetes insipidus. She was treated with steroid,nasal desmopressin, and insulin for her steroid induced diabetes mellitus. Cranial CT scan showed a large enhancing lesion involving the entire midbrain, hypothalamus, and the thalamic regions. She developed respiratory arrest on July 15,2001 and was pronounced dead.

　She was discussed in a neurological CPC and the chief discussant arrived at the conclusion that the patient had a primary malignant lymphoma of the brain. Clinical diagnosis in the early stage of her disease was neurosarcoidosis.

　Post-mortem examination revealed a mass continuously involving the pons, midbrain, hypothalamus, thalamus, and the putamen. The optic chiasm was enlarged. By histologic examination, the mass consisted of dense medium sized tumor cells. Immunohistologic observation revealed that the tumor cells were B-cell type malignant lymphoma. No tumor cells were found in the systemic organs.