Nocardia arthritidisによる播種性ノカルジア症に合併したと考えられる内因性網膜下膿瘍の1例

A case of presumed endogenous subretinal abscess due to disseminated nocardiosis caused by Nocardia arthritidis

要約　目的：ノカルジア肺炎を契機に，播種性ノカルジア症による内因性網膜下膿瘍を発症した1例を経験したので報告する。

症例：72歳，女性。2017年から尋常性天疱瘡に対しステロイドと免疫抑制薬の内服で加療されていた。2020年6月，ノカルジア肺炎を契機に播種性ノカルジア症による脳膿瘍と左内直筋膿瘍を発症した。同時期に，近医の眼底検査で，左眼の後極部耳側の網膜下に黄白色の隆起病変が認められた。

所見：当科再診時の矯正視力は右0.2，左は0.8で，両眼とも前眼部や中間透光体に炎症細胞の浸潤はなかった。眼底検査では，左眼の後極部耳側の網膜下に境界明瞭な黄白色の隆起病変を認めた。肺胞洗浄液の細菌培養検査でNocardia arthritidisが同定されていたことから，左眼の網膜下病変は同細菌による内因性網膜下膿瘍であると推定した。抗菌薬の全身投与を開始したところ左眼の網膜下膿瘍は著明に縮小し，最終受診時の左矯正視力は1.2まで改善し，良好な経過をたどった。

結論：免疫不全宿主のノカルジア症は血行性に播種することがあり，眼病変にも注意する必要がある。ノカルジア内因性眼内炎の診断は，肺胞洗浄液の細菌培養検査など眼以外の組織の培養が手がかりとなることがある。

Abstract　Purpose：We report a case of endogenous subretinal abscess due to disseminated nocardiosis triggered by Nocardia pneumonia.

Case：The patient was a 72-year-old woman, who was being treated with steroids and immunosuppressants for pemphigus vulgaris since 2017. In June 2020, she developed brain an abscesses and abscess in the left medial rectus muscle due to disseminated nocardiosis triggered by Nocardia pneumonia. At the same time, a fundus examination at an ophthalmology clinic revealed a yellowish-white elevated subretinal lesion on the temporal side of the posterior pole of the left eye.

Findings：The best corrected visual acuity was 0.2 in the right eye and 0.8 in the left, and there were no inflammatory cells in the anterior chamber or vitreous body in both eyes. A fundus examination revealed a yellowish-white elevated subretinal lesion with a well-defined border on the temporal side of the posterior pole of the left eye. Since Nocardia arthritidis was detected on culture of bronchoalveolar lavage fluid, the subretinal lesion in the left eye was presumed to be an endogenous subretinal abscess caused by it. Systemic antibacterial medications were initiated, and the subretinal abscess in the left was markedly reduced. The final best corrected visual acuity was 1.2 in the left, which was a favorable outcome.

Conclusions：Nocardia infections in immunocompromised hosts can be hematogenously disseminated, and attention should be paid to ocular lesions. Specimens from organs other than the eye, such as the culture of bronchoalveolar lavage fluid, may assist in the diagnosis of endogenous Nocardia endophthalmitis.