外眼筋を巻き込み治療困難であったMALTリンパ腫の1例

A recalcitrant case of MALT lymphoma involving the extraocular muscles

要約　目的：外眼筋に浸潤し，治療が困難であったmucosa-associated lymphoid tissue（MALT）リンパ腫の症例の報告。症例：60歳男性が3か月前からの右眼下眼瞼付近の腫瘤と複視で受診した。所見：矯正視力は右0.7，左1.0で，硬結のある腫瘤が右眼の下眼瞼にあり，右眼の下転障碍があった。コンピュータ断層撮影で33mm×35mm×30mmの充実性腫瘤があった。眼窩腫瘍摘出の術中所見として，腫瘍は球後の視神経近くに及び，外眼筋，下直筋，下斜筋を巻き込んでいた。全摘を諦め可能な範囲を摘出した。プレドニゾロンを術後3週間投与した。摘出組織は病理学的にMALTリンパ腫と診断された。全身転移はなく，術後6か月後の現在，複視は軽減し1.0の矯正視力を得ている。結論：MALTリンパ腫は緩慢な経過をとることが多いが，本症例では急速な経過をとり，外眼筋を含む広い範囲に浸潤していた。

Abstract.　Purpose：To report a case of mucosa-associated lymphoid tissue（MALT）lymphoma that posed difficulties in the treatment. Case：A 60-year-old male presented with diplopia and tumor in the right lower eyelid since 3 months before. Findings：Corrected visual acuity was 0.7 right and 1.0 left. A solid tumor was present in the right lower eyelid with restricted downward motility of eyeglobe. Computed tomography（CT）showed a tumor mass of 33 mm×35 mm×30 mm in size. As intraoperative finding,the tumor reached the retrobulbar portion of optic nerve and involved the lateral and inferior rectus muscle and lower oblique muscle. As total removal was not possible,the tumor was resected as far as possible. The patient was treated by peroral prednisolone for 3 weeks after surgery. The removed tissue was diagnosed with MALT lymphoma. No metastasis was detected. After 6 months of surgery,the patient is doing well with reduced diplopia and visual acuity of 1.0. Conclusion：MALT lymphoma is characterized by slow progression in general. The present case illustrates that it may take an acute course infiltrating the orbital tissue including the extraocular muscles.