Idiopathic CD4+ lymphocytopenia (ICL) is a rare disorder characterized by low counts of CD4+ cells (<300/mm3) in absence of other known causes of immunosuppression. A few cases of progressive multifocal leukoencephalopathy (PML) were reported in association with ICL with variable outcome. We describe the case of a 40 year-old man diagnosed with PML, which showed a monophasic course. Causes of primary and secondary immunodeficiency were ruled out, only a "borderline" ICL was found. This case highlights that a severe immunodepression could not be an absolute prerequisite in developing PML and also points the attention on current definition of ICL.

中文翻译：

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“边缘性”特发性 CD4+ T 细胞淋巴细胞减少症表现为非典型进行性多灶性白质脑病

特发性 CD4+ 淋巴细胞减少症 (ICL) 是一种罕见的疾病，其特征是在没有其他已知的免疫抑制原因的情况下，CD4+ 细胞计数低 (<300/mm3)。据报道，一些进展性多灶性白质脑病 (PML) 病例与 ICL 相关，结果各不相同。我们描述了一个被诊断患有 PML 的 40 岁男性的病例，该病例呈单相病程。排除了原发性和继发性免疫缺陷的原因，只发现了“边缘”ICL。这个案例强调了严重的免疫抑制不能成为发展 PML 的绝对先决条件，也指出了对 ICL 当前定义的关注。