白点症候群様の所見を呈し診断に苦慮した原発性硝子体網膜リンパ腫の1例

A case of primary vitreoretinal lymphoma resembling the white dot syndromes

要約　目的：原発性硝子体網膜リンパ腫（PVRL）は，多彩な所見を呈し，その診断の困難さから眼内炎症として加療されることも多く，仮面症候群と呼ばれている。今回，病初期に白点症候群様の所見を呈し，診断に苦慮したPVRLの症例を経験したので報告する。

症例：50歳，女性。左眼の見えにくさを主訴に受診した。初診時視力は両眼とも（1.2），左眼に前部硝子体細胞および眼底中間周辺部に散在する白点を認めた。6か月間ベタメタゾン点眼で加療したが，眼内炎症および白点の改善はみられなかった。トリアムシノロン後部テノン囊下注射を施行後，プレドニゾロン内服を開始したところ，網膜滲出斑の出現と硝子体混濁の急激な増悪を認めた。PVRLを疑ったが，真菌などによる感染性ぶどう膜炎の可能性も考え，フルコナゾール点滴を行った。左視力がさらに低下したため硝子体生検を施行し，IL-10/IL-6＞1，IgH遺伝子再構成を認めた。全身精査にて眼外病変はなく，PVRLと診断した。メトトレキサートの硝子体注射および全身投与を開始した。現在まで左視力の改善はないものの，右眼の発症はなく，脳・中枢神経播種もみられていない。

結論：PVRLはぶどう膜炎や白点症候群に類似の所見を呈することがあるため，その可能性を念頭に置く必要があると考えられた。

Abstract　Purpose：Primary vitreoretinal lymphoma（PVRL）is often referred to as a masquerade syndrome and is treated as an intraocular inflammatory disease, because it presents with a variety of findings and is difficult to diagnose. We herein report a case of PVRL with white dot syndromes-like findings in the early stages of the disease, which was challenging to diagnose.

Case：A 50-year-old woman presented with a chief complaint of difficulty in seeing from her left eye. She was treated with betamethasone eye drops for 6 months, but the intraocular inflammation and white dots did not improve. She received sub-Tenon's triamcinolone acetonide injection in the left eye following which oral prednisolone was initiated. However, retinal exudates appeared, and the vitreous opacity rapidly worsened. Besides PVRL, we considered the possibility of infectious uveitis caused by fungi and initiated treatment with fluconazole drops. Visual acuity in the left eye decreased, and vitreous biopsy was performed for suspected PVRL. Interleukin（IL）-10/IL-6＞1 in the vitreous fluid and rearranged IgH gene were observed. Based on these findings and in the absence of extraocular lesions on systemic examination, PVRL was diagnosed. Methotrexate was systemically and intravitreally administered. Visual acuity in the left eye did not improve, and the right eye remained intact. No central nervous system dissemination has been observed to date.

Conclusion：PVRL should be considered among the differential diagnosis, because PVRL may present with findings similar to those of uveitis and white dot syndromes.