ステロイド局所投与によって軽快した樹氷状血管炎の1例

An example of frosted branch angiitis relieved by local administration of steroids

要約　目的：樹氷状血管炎は何らかの感染症に伴うアレルギー性の炎症反応による網膜血管炎であると考えられ，通常ステロイド薬の全身投与が著効する。今回，若年女性のウイルス感染症を契機に発症した樹氷状血管炎に対してステロイド薬（メチルプレドニゾロン酢酸エステル懸濁注射液）のテノン囊下注射とベタメタゾンリン酸エステルの点眼治療により改善に至った1例を経験したので報告する。

症例：19歳，女性。高熱，頭痛，眩暈，嘔気を認め，他病院でウイルス感染症と診断され入院加療中であった。抗菌薬および抗ウイルス薬の投与開始後に両眼の視力低下を自覚し，関西医科大学附属病院を紹介され受診となった。矯正視力は右0.01，左0.02であった。両眼とも広範囲に網膜静脈の白鞘化を，また黄斑部に浮腫と漿液性網膜剝離を認めた。フルオレセイン蛍光造影眼底検査では，樹氷状血管炎に特徴的な網膜静脈からの蛍光漏出を認めた。血液検査を含む全身検査では有意な所見はなく，前房水PCRでヘルペスウイルス属は検出されなかった。以上の所見から，樹氷状血管炎と確定診断した。両眼に前述のステロイド薬のテノン囊下注射と点眼治療を行い，治療後3か月時点で両眼ともに網膜静脈の白鞘化の色調ならびに黄斑部の異常所見は消失した。治療数か月後に矯正視力は両眼とも1.0に改善した。

結論：樹氷状血管炎にはステロイド薬の全身投与が著効するが，局所投与であっても治療効果が良好な症例がある。

Abstract　Purpose：Frosted branch angiitis is retinal vasculitis that develops due to an allergic inflammatory reaction associated with some infection and is treated effectively by administration of systemic steroids. We report the case of a young woman with frosted branch angiitis caused by a viral infection. She was treated by irrigation of sub-Tenon's steroid（methylprednisolone phosphate suspension）injection and instillation of betamethasone phosphate.

Case：A 19 year old woman with fever, headache, dizziness, and nausea underwent inpatient treatment for a viral infection diagnosed at another hospital. After administration of anti-bacterial and viral drugs, she became aware of vision loss in both eyes. She was referred to Kansai Medical University Hospital. The best corrected decimal visual acuity was 0.01 for the right eye and 0.02 for the left eye. Fundus examination showed bilateral retinal vasculitis with venous, macular edema and serous retinal detachment. Fluorescein angiography demonstrated leakage from the retinal vein with vasculitis. There were no remarkable findings with systemic examination including blood test. Moreover, herpesvirus genus were not detected by PCR of anterior chamber aqueous humor. Based on the above findings, she was diagnosed with frosted branch angiitis. Subsequently, instillation and sub-Tenon's steroid irrigation were performed in both eyes. A few months after treatment, post-best corrected decimal visual acuity was improved to 1.0 in both eyes. Abnormal findings of retinal vasculitis with venous, macular edema disappeared.

Conclusion：Systemic steroid administration is quite effective for treatment of frosted branch angiitis. Topical administration of steroids can also be effective for frosted branch angiitis.