sIL-2R高値で脈絡膜炎を呈したネコひっかき病にステロイド治療が奏効した1例

A case of cat scratch disease with choroiditis and elevated sIL-2R levels successfully treated with steroids

要約　目的：可溶性IL-2レセプター（sIL-2R）高値で脈絡膜炎を呈したネコひっかき病（CSD）に対し，治療が著効した症例を報告する。

症例：10歳，女児。2024年12月より1週間続く不明熱で前医小児科に入院した。CRP 2.99mg/dL，sIL-2R 1,128U/mLであった。発熱10日目に左眼霧視を訴え，両眼に脈絡膜白色隆起病変，網膜下液，前後眼部炎症を認め，当科紹介となった。視力は右1.5（矯正不能），左は（0.07）まで低下していた。感染性の全身・網膜病巣を疑い，抗菌薬点滴による加療を開始したが，治療への反応性は乏しかった。その10日後には眼病変に対してステロイド点眼も開始したが，病巣の改善はなかった。第34病日に左眼に局所ステロイド注射を実施した。左眼の漿液性網膜剝離は消失し，病変は縮小した。第41病日にプレドニゾロン（PSL）30mgの内服を開始し，解熱した。第23病日に採取したBartonella henselae抗体陽性でCSDと診断し，抗菌薬をリファンピシン＋スルファメトキサゾール・トリメトプリム合剤に変更した。両眼の病変は縮小し，第54病日に左矯正視力は0.7に回復し，sIL-2Rは480U/mLまで低下して退院した。最終受診時の矯正視力は両眼とも1.5まで改善した。

結論：ステロイドは遷延性発熱を伴うCSDに有効であり，sIL-2Rは病勢を反映する指標となる可能性がある。

Abstract　Purpose：To report a case of cat scratch disease（CSD） presenting with choroiditis and elevated soluble interleukin-2 receptor（sIL-2R） levels, in which corticosteroid therapy demonstrated remarkabl efficacy.

Case：A 10-year-old girl was admitted to a local pediatric department with a one-week history of fever of unknown origin. Laboratory investigations revealed an elevated C-reactive protein level of 2.99 mg/dL and sIL-2R level of 1,128 U/mL. On day 10 of fever, she reported blurred vision in her left eye. Ophthalmologic examination revealed bilateral elevated white choroidal lesions with subretinal fluid and anterior segment inflammation. Best-corrected visual acuity（BCVA） was 1.5 in the right eye and 0.07 in the left eye. Empirical antibiotic therapy was initiated for suspected systemic or infectious retinochoroiditis, but yielded minimal improvement. Ten days later, topical corticosteroids were added, with limited effect. On day 34, a sub-Tenon's triamcinolone acetonide injection was administered to the left eye, resulting in the resolution of the serous retinal detachment and reduction of the choroidal lesion. On day 41, oral prednisolone（30 mg/day） was initiated, leading to rapid defervescence. Serologic testing on day 23 was positive for Bartonella henselae antibodies, confirming the diagnosis of CSD. Antimicrobial therapy was subsequently switched to rifampicin combined with trimethoprim-sulfamethoxazole, resulting in further improvement. On day 54, the BCVA in the left eye improved to 0.7, and the sIL-2R level had decreased to 480 U/mL. The patient was discharged in good condition, and at the final follow-up, BCVA was 1.5 bilaterally.

Conclusion：Corticosteroid therapy proved effective in managing CSD with prolonged fever and ocular inflammation. The sIL-2R level may serve as a useful biomarker for assessing systemic disease activity in CSD.