脳脊髄液中のJCV-DNA遺伝子検査が2回とも陰性であったが，開頭脳生検で診断確定したHIV関連進行性多巣性白質脳症の1例

Progressive Multifocal Leukoencephalopathy Associated with HIV Infection Diagnosed by Brain Biopsy with Repeated Negative PCR Testing of CSF JC Virus DNA

症例は36歳男性。亜急性に進行する小脳性運動失調で受診した。頭部MRIで左小脳半球と右頭頂葉深部白質に病変を認めた。ヒト免疫不全ウイルス（HIV）感染症例であり，HIV脳症や進行性多巣性白質脳症（PML）が疑われたため，HIV感染に対しARTを開始した。一時的に症状は改善したが，再び神経症状が増悪し，白質病変のMRI Gd造影効果が出現した。HIV関連PML（HIV-PML）による免疫再構築症候群が強く疑われたが，脳脊髄液中JCウイルス（JCV）-DNA検査は2回とも陰性であった。開頭脳生検では，JCVが高copy数存在し，異型リンパ球など悪性リンパ腫を示唆する所見は認めなかったことよりHIV-PMLの診断確定に至った。脳脊髄液中JCV-DNAが繰り返し陰性であっても，PMLが疑われる場合は診断確定のために脳生検も考慮すべきである。

Abstract

A 36-year-old man with human immunodeficiency virus (HIV) infection was admitted to our hospital due to progressive ataxia. Brain MRI demonstrated high-signal intensity in the white matter of the right parietal lobe and left cerebellar hemisphere on T2-weighted images. Despite antiretroviral therapy, as his clinical symptoms worsened and MRI lesions gradually increased with the appearance of gadolinium-enhanced lesions, immune reconstitution inflammatory syndrome by progressive multifocal leukoencephalopathy (PML) associated with HIV infection was suspected. However, JC virus (JCV) in the cerebrospinal fluid (CSF) was undetectable by DNA PCR twice. Therefore, biopsy of the right parietal lobe was performed. JCV DNA was detected by PCR using the biopsy sample. JC viral protein was also identified by immunohistochemistry. Brain biopsy should be considered for the clinical diagnosis of PML when CSF JCV is negative on repeated DNA PCR.

(Received September 20, 2019; Accepted January 14, 2020; Published May 1, 2020)