視細胞外節異常から診断に至ったacute syphilitic posterior placoid chorioretinitisの1例

A case of acute syphilitic posterior placoid chorioretinitis appearing with photoreceptor outer segment abnormalities

要約　目的：Acute syphilitic posterior placoid chorioretinitis（ASPPC）は梅毒2期以降に出現する梅毒ぶどう膜炎のなかでも稀な病態である。今回，眼科受診で比較的軽度な後眼部所見と光干渉断層計（OCT）で視細胞外節異常を呈し，最終的に梅毒と診断に至ったASPPCを経験したため，臨床所見と画像所見を報告する。

症例：42歳，男性。1週間前から右眼視力低下を自覚し，球後視神経炎の疑いで帝京大学医学部附属溝口病院を紹介され受診となった。右視力（0.2），黄斑周囲の淡黄色の変化とOCTで視細胞外節の不鮮明化を認めた。右眼前房・硝子体中の炎症所見を認めず，視神経乳頭に異常はなかった。右眼は中心暗点を認め，中心フリッカ値は低下していた。血清学的検査で梅毒感染が確認され，ASPPCの診断に至った。右眼の症状は梅毒加療開始前に自然軽快した。髄液検査で神経梅毒の診断となり，ベンジルペニシリンによる点滴加療を施行したが，その3か月後に右眼に同症状が再発した。さらに，点滴抗菌薬加療が追加されてからは，症状の再燃を認めなかった。

結論：視細胞外節異常を呈する網膜病変は梅毒感染である可能性があり，全身検索と早期加療を行う必要がある。

Abstract　Purpose：Acute syphilitic posterior placoid chorioretinitis（ASPPC）is a rare manifestation of syphilitic uveitis which appears in stage 2 syphilis or later. We report clinical and image findings of a case of ASPPC, which first showed mild posterior manifestation with abnormal photoreceptor outer segment in optical coherence tomography（OCT）, and later was diagnosed as syphilis.

Case：A 42-year-old man was referred to our hospital who was suspected to have optic neuritis because of decreased vision of his right eye for 1 week. His corrected visual acuity was 0.2, his retina showed yellowish changes of macula and OCT showed unclear photoreceptor outer segments. Inflammation in anterior chamber and vitreous was not obvious and optic disc was normal. His right eye showed central scotoma and central flicker was decreased. Serological examination revealed infection of syphilis and ASPPC was confirmed. His retinal abnormality was spontenously recovered before the treatment of syphilis. Lumbar puncture made diagnosis of neuronal syphilis and benzylpenicillin was injected into him. Three months later, retinal abnormality recurred and additional antibiotics was injected, which caused complete disappearance of retinal abnormality.

Conclusion：Retinal lesion with photoreceptor outer segment abnormalities can be caused by syphilitic infection. Systemic evaluation and early treatment are needed in such a case.