上顎洞悪性神経鞘腫に対する重粒子線治療後に生じた眼窩有害事象の1例

Orbital adverse events following heavy particle therapy for schwannoma: a case report

要約　目的：右上顎洞悪性神経鞘腫に対する重粒子線治療後に右眼窩内にさまざまな有害事象を認めた1例を報告する。

症例：神経線維腫症1型の27歳，男性。右眼の違和感を自覚し，当科を初診した。初診時右視力（1.2），右眼圧21mmHg，右眼下転制限を認めた。頭部CTにて右上顎洞腫瘍を指摘され生検したところ，右上顎洞悪性神経鞘腫と診断された。右上顎洞から眼窩内まで浸潤をきたし，切除不能のため重粒子線治療（70.4Gy/16Fr）を施行した。

所見：治療5か月後に出血性ショックと感染を起こすも腫瘍自体は縮小した。右顔面拘縮は進行し，治療1年半後に右続発性緑内障と放射線網膜症を発症し右眼光覚は消失した。眼痛，嘔吐が増悪し，毛様体光凝固術を施行したが右眼球癆に至った。治療4年7か月後に繰り返す多量の右結膜下出血を認め，CTで鼻腔内からの出血を指摘された。治療8年3か月後に眼瞼拘縮の進行による兎眼を発症した。同時期に右上顎洞に細菌感染を認め，右眼瞼腫脹，結膜浮腫，結膜出血，排膿をきたし，抗菌薬の点滴加療で改善した。

結論：重粒子線治療後に多様な眼窩有害事象が発症するため，長期にわたる経過観察が必要である。

Abstract　Objective：We report a case of orbital adverse events following heavy particle therapy for a malignant schwannoma of the right maxillary sinus.

Case：A 27-year-old man with neurofibromatosis type 1 presented with discomfort in his right eye. His decimal visual acuity was 1.2, intraocular pressure was 21 mmHg, and ocular motility was restricted to downward gaze. Head computed tomography revealed a right maxillary sinus tumor, which was diagnosed as a malignant schwannoma on biopsy. Because the tumor extended from the right maxillary sinus into the orbit, surgical resection was not feasible. The patient, therefore, underwent heavy particle therapy（70.4 Gy in 16 fractions）.

Results：Five months after treatment, the patient developed right facial contracture. Eighteen months post-treatment, secondary glaucoma and radiation retinopathy occurred resulting in complete loss of light perception. He subsequently experienced severe ocular pain and vomiting, which necessitated ciliary photocoagulation of the right eye. Four years and seven months post-treatment, recurrent massive subconjunctival hemorrhages occurred due to bleeding from a right maxillary sinus hemorrhage that extended directly into the subconjunctival space. Eight years after treatment, progressive facial contracture led to right lagophthalmos. Concurrently, a bacterial infection developed in the right maxillary sinus, causing eyelid swelling, conjunctival edema, subconjunctival hemorrhage, and purulent discharge. The infection improved following intravenous antibiotics therapy.

Conclusion：A long-term follow-up is required following heavy particle therapy.