We present a case of a 58-year-old man with a history of severe discoid lupus erythematosus and acute encephalopathy and incoordination. Antinuclear antibody testing was weakly positive but all other laboratory tests for systemic lupus erythematosus were negative and serum quantitative immunoglobulins and lymphocytes were normal. MRI brain showed T2/FLAIR hyperintensities within the bilateral parietal and temporal lobes with involvement of subcortical U fibers. CSF PCR was negative for varicella-zoster virus, herpes simplex, JCV and BK virus. However, JCV antibody index was elevated (3.88; reference: < 0.2). Right parietal brain biopsy was consistent with JCV infection and diagnostic of progressive multifocal leukoencephalopathy (PML). To the best of our knowledge, this is the first reported case of PML in a patient with discoid lupus without other traditional risk factors for the disease and highlights the need for clinical vigilance in this patient population.

我们介绍一例 58 岁男性病例，有严重盘状红斑狼疮、急性脑病和运动失调病史。抗核抗体检测呈弱阳性，但系统性红斑狼疮的所有其他实验室检测均为阴性，血清定量免疫球蛋白和淋巴细胞正常。大脑 MRI 显示双侧顶叶和颞叶内 T2/FLAIR 高信号，并累及皮质下 U 纤维。脑脊液 PCR 检测水痘带状疱疹病毒、单纯疱疹病毒、JCV 和 BK 病毒呈阴性。然而，JCV抗体指数升高（3.88；参考值：<0.2）。右顶脑活检结果与 JCV 感染和进行性多灶性白质脑病 (PML) 的诊断一致。据我们所知，这是首例报告的盘状狼疮患者发生 PML 病例，且没有该疾病的其他传统危险因素，这凸显了对该患者群体进行临床警惕的必要性。