両眼球結膜下出血と右視力低下をきっかけに両眼窩MALTリンパ腫と診断された1例

A case of bilateral orbital MALT lymphoma diagnosed following bilateral subconjunctival hemorrhage and decreased right visual acuity

要約　目的：両眼球結膜下出血と右視力低下の初発症状をきっかけとし，眼窩の粘膜関連リンパ組織リンパ腫（MALTリンパ腫）と診断・治療された1例を経験したので報告する。

症例：64歳，男性。3年前から両眼結膜下出血を自覚していた。X年7月に全身の複数リンパ節の腫脹を認め骨髄生検が実施されたが，異型B細胞浸潤を認めるのみで経過観察となっていた。X年9月に急激な右視力低下を主訴に当科を受診した。右矯正視力低下，両眼水平方向の眼球運動障害，眼球突出，眼球結膜下出血，外斜視を認めた。両眼球結膜外側に腫瘤性病変を認め，右眼フリッカ値は低下しており，右視神経萎縮が進行していた。採血検査では可溶性IL-2レセプター高値であった。眼窩MRIで両涙腺の腫大と視神経に沿った腫瘍性病変を認め，右眼窩腫瘍生検でMALTリンパ腫の診断となった。ベンダムスチン・リツキシマブ（BR）療法が行われ，眼窩腫瘍の軽減，右矯正視力の改善を認めた。

結論：非典型的症状を伴って発症した，全身性悪性リンパ腫の眼窩転移と考えられる症例を経験した。化学療法が奏効したが再発リスクの高い症例であり，今後の経過観察が重要である。

Abstract　Purpose：We report a case of orbital mucosa-associated lymphoid tissue（MALT） lymphoma that initially presented with bilateral subconjunctival hemorrhage and decreased visual acuity in the right eye.

Case：A 64-year-old man had been aware of bilateral subconjunctival hemorrhage since at least three years prior（X−3）. In July of year X, he developed multiple systemic lymphadenopathies. Bone marrow biopsy showed infiltration of atypical B cells, and he was placed under observation. In September of year X, he presented to our department with acute onset of impaired his right vision. Examination revealed decreased corrected visual acuity in the right eye, limitation of horizontal ocular movements in both eyes, proptosis, subconjunctival hemorrhage, and exotropia. Tumorous lesions were observed on the lateral conjunctiva of both eyes. Flicker value in the right eye were decreased, with progressive optic atrophy. Blood tests revealed elevated soluble IL-2 receptor. Orbital MRI demonstrated enlargement of both lacrimal glands and tumor lesions along the optic nerve. Orbital tumor biopsy of the right eye confirmed the diagnosis of MALT lymphoma. Bendamustine-rituximab（BR） therapy was administered, resulting in reduction of the orbital tumor and improvement of corrected visual acuity in the right eye.

Conclusion：We encountered a case that presented with atypical symptoms and was considered to represent orbital metastasis of systemic malignant lymphoma. Although chemotherapy was effective, the patient is at high risk of recurrence, and careful long-term follow-up is warranted.