単独の動眼神経麻痺で初発した悪性リンパ腫の1例

A case of malignant lymphoma presenting as isolated oculomotor nerve palsy

要約　目的：単独の動眼神経麻痺（ONP）で初発した悪性リンパ腫の症例報告。

症例：74歳女性が右眼の眼瞼下垂，複視を主訴に初診した。高血圧，心房細動の既往があり，左眼は先天ぶどう膜欠損により生来弱視で白内障手術歴があった。視力は右（0.9），左（0.09）。右眼は眼瞼下垂，内転・上転・下転の運動障害があり，瞳孔異常のないpupil sparing型のONPを呈していた。眼内は初発白内障の他に特記すべき所見はなかった。左眼はぶどう膜欠損による瞳孔の下方偏位と眼内レンズ挿入眼を認めた。頭部単純MRIとMRAで異常はなかった。熱発，全身倦怠感，食欲不振が生じ，採血で胆道系酵素とC反応性蛋白の上昇を認めた。胸腹部の精査にて多発リンパ節腫大，左扁桃腫大，胃壁肥厚，右副腎腫大，肝腫瘤，子宮と膀胱の腫大，左大腿骨骨幹部の軟部陰影を認め，悪性疾患の多発転移が疑われた。扁桃と胃の生検からびまん性大細胞型B細胞リンパ腫と診断された。髄液検査で異常細胞はなく，頭部造影MRIで右海綿静脈洞に増強効果を認めた。化学療法（R-THP-COP療法）とメトトレキサートの髄腔内注射を行った。治療後，ONPは軽快し寛解が得られたが，初診から14か月目に再発し4か月後に死亡した。

結論：単独のONPを初発とした悪性リンパ腫の1例を経験した。頭蓋内に器質的異常を認めないONPに遭遇した場合も，悪性リンパ腫を念頭に置く必要があると思われた。

Abstract　Objective：To report a case of isolated oculomotor nerve palsy（ONP）as a manifestation of malignant lymphoma.

Case：A 74-year-old woman, with a history of hypertension and atrial fibrillation, was first admitted to our hospital following sudden right ptosis and diplopia. She also had a history of cataract surgery and left eye amblyopia due to a congenital uveal deficiency. Best corrected visual acuity was 0.9 in the right eye and 0.09 in the left eye. The right eye had ptosis and the ocular motility examination showed a limitation in adduction, elevation and depression, as well as, pupil sparing-type ONP. There were no remarkable findings in her right eye except incipient cataract. The left eye showed a downward deviation of the pupil due to a defect in the uveal tract and an intraocular lens. Brain magnetic resonance imaging（MRI）and MR angiography（MRA）were unremarkable. Fever, general malaise, and appetite loss occurred, and she was found to have an elevated serum C-reactive protein and biliary enzymes. Metastasis of malignancy was suspected due to multiple lymphadenopathy, tonsillar swelling, gastric wall thickening, right adrenal gland swelling, liver mass, uterine and bladder swelling, left femur diaphysis mass on chest and abdominal computed tomography. The histopathologic examination of the tonsil and stomach biopsy revealed diffuse large B-cell lymphoma. The cerebrospinal fluid cytology identified no malignant cells, and enhanced brain MRI showed an enhancement of the right cavernous sinus. Chemotherapy（rituximab, vincristine, pirarubicin, cyclophosphamide, prednisolone）and intrathecal injection of methotrexate were initiated. After treatment, the patient's general condition and ONP gradually improved and remission was obtained, but relapsed 14 months after the first visit and died 4 months later.

Conclusion：An isolated ONP presenting as the primary manifestation of a malignant lymphoma is rare. This case suggests the necessity to consider malignant lymphoma, if ONP with no organic abnormalities in the skull is observed.