進行性多巣性白質脳症をきたした全身性エリテマトーデスの一例 A case of progressive multifocal leukoencephalopathy associated with systemic lupus erythematosus

  全身性エリテマトーデス（SLE）の経過中に進行性多巣性白質脳症（PML）を発症した1例を経験したので報告する．症例は57歳女性．2000年SLEと診断され，2004年よりメチルプレドニゾロン16 mg/日を投与されていた．2005年9月，発熱，顔面・四肢の紅斑を生じ，当科紹介入院．播種性クリプトコッカス症と診断し，抗真菌薬の投与により軽快した．その後，多関節炎，四肢紅斑，低補体血症などSLEの再燃を認めたため，11月下旬よりプレドニゾロン40 mg/日に増量された．12月末より，失見当識，記銘力低下を生じ，脳MRIにて右前頭葉皮質下白質に占拠性病変を認めた．開頭脳生検による脳病理組織所見及びPCR法にて脳脊髄液中のJCウイルスDNA陽性を認めたことからPMLと診断した．PMLは中枢神経系に脱髄病変をきたす致死的病態であり，AIDS患者における日和見感染症として知られている．自己免疫疾患患者においても免疫抑制薬や生物学製剤使用に関連して，PMLを発症することが注目されている．SLEの経過中，亜急性の中枢神経障害，脳白質病変を認めた場合にはPMLを鑑別診断としてあげる必要があり，文献的考察を含めて報告する．

  We describe a case of systemic lupus erythematosus (SLE) complicated with multifocal leukoencephalopathy (PML). A 57-year old woman, who had a five-year history of SLE, was admitted to our hospital because of fever and multiple subcutaneous nodules. Diagnosis of disseminated cryptococcosis was made based on histological and bacteriological examinations, and she was successfully treated with anti-fungal drugs. Corticoteroids were increased for persistent lupus activities. One month later, however, she gradually developed disorientation and short-term memory loss. A brain magnetic resonance image (MRI) showed a focal lesion in the white matter of the right frontal lobe. Brain biopsy demonstrated demyelinating lesions with the presence of JC viral antigen. Polymerase chain reaction also revealed JC virus DNA in the cerebrospinal fluid. Her condition gradually progressed, and she died a year later due to pneumonia. Although acquired immunodeficiency syndrome is currently the most common disease associated with PML, patients with autoimmune diseases receiving immunosuppressive therapy also have risks for developing PML. In patients with SLE presenting with subacute neurological abnormalities and white matter lesions in the brain, PML should be considered in the differential diagnosis.